drm/dp: Move DisplayPort helpers into separate helper module

Move DisplayPort functions into a separate module to reduce the size
of the KMS helpers. Select DRM_DP_HELPER for all users of the code. To
avoid naming conflicts, rename drm_dp_helper.c to drm_dp.c

This change can help to reduce the size of the kernel binary. Some
numbers from a x86-64 test build:

Before:
	drm_kms_helper.ko:	447480 bytes

After:
	drm_dp_helper.ko:	216632 bytes
	drm_kms_helper.ko:	239424 bytes

For early-boot graphics, generic DRM drivers, such as simpledrm,
require DRM KMS helpers to be built into the kernel. Generic helper
functions for DisplayPort take up a significant portion of DRM KMS
helper library. These functions are not used by generic drivers and
can be loaded as a module.

v3:
	* fix include statement in DRM selftests
v2:
	* move DP helper code into dp/ (Jani)

Signed-off-by: Thomas Zimmermann <[email protected]>
Acked-by: Lyude Paul <[email protected]>
Acked-by: Daniel Vetter <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

1 files changed, 0 insertions, 5977 deletions

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
deleted file mode 100644
index bc3237a09c06..000000000000
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ /dev/null
@@ -1,5977 +0,0 @@
-/*
- * Copyright © 2014 Red Hat
- *
- * Permission to use, copy, modify, distribute, and sell this software and its
- * documentation for any purpose is hereby granted without fee, provided that
- * the above copyright notice appear in all copies and that both that copyright
- * notice and this permission notice appear in supporting documentation, and
- * that the name of the copyright holders not be used in advertising or
- * publicity pertaining to distribution of the software without specific,
- * written prior permission.  The copyright holders make no representations
- * about the suitability of this software for any purpose.  It is provided "as
- * is" without express or implied warranty.
- *
- * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
- * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
- * EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
- * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
- * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
- * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
- * OF THIS SOFTWARE.
- */
-
-#include <linux/bitfield.h>
-#include <linux/delay.h>
-#include <linux/errno.h>
-#include <linux/i2c.h>
-#include <linux/init.h>
-#include <linux/kernel.h>
-#include <linux/random.h>
-#include <linux/sched.h>
-#include <linux/seq_file.h>
-#include <linux/iopoll.h>
-
-#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
-#include <linux/stacktrace.h>
-#include <linux/sort.h>
-#include <linux/timekeeping.h>
-#include <linux/math64.h>
-#endif
-
-#include <drm/drm_atomic.h>
-#include <drm/drm_atomic_helper.h>
-#include <drm/drm_dp_mst_helper.h>
-#include <drm/drm_drv.h>
-#include <drm/drm_print.h>
-#include <drm/drm_probe_helper.h>
-
-#include "drm_dp_helper_internal.h"
-#include "drm_dp_mst_topology_internal.h"
-
-/**
- * DOC: dp mst helper
- *
- * These functions contain parts of the DisplayPort 1.2a MultiStream Transport
- * protocol. The helpers contain a topology manager and bandwidth manager.
- * The helpers encapsulate the sending and received of sideband msgs.
- */
-struct drm_dp_pending_up_req {
-	struct drm_dp_sideband_msg_hdr hdr;
-	struct drm_dp_sideband_msg_req_body msg;
-	struct list_head next;
-};
-
-static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
-				  char *buf);
-
-static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port);
-
-static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
-				     int id,
-				     struct drm_dp_payload *payload);
-
-static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
-				 struct drm_dp_mst_port *port,
-				 int offset, int size, u8 *bytes);
-static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
-				  struct drm_dp_mst_port *port,
-				  int offset, int size, u8 *bytes);
-
-static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
-				    struct drm_dp_mst_branch *mstb);
-
-static void
-drm_dp_send_clear_payload_id_table(struct drm_dp_mst_topology_mgr *mgr,
-				   struct drm_dp_mst_branch *mstb);
-
-static int drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
-					   struct drm_dp_mst_branch *mstb,
-					   struct drm_dp_mst_port *port);
-static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
-				 u8 *guid);
-
-static int drm_dp_mst_register_i2c_bus(struct drm_dp_mst_port *port);
-static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_mst_port *port);
-static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr);
-
-static bool drm_dp_mst_port_downstream_of_branch(struct drm_dp_mst_port *port,
-						 struct drm_dp_mst_branch *branch);
-
-#define DBG_PREFIX "[dp_mst]"
-
-#define DP_STR(x) [DP_ ## x] = #x
-
-static const char *drm_dp_mst_req_type_str(u8 req_type)
-{
-	static const char * const req_type_str[] = {
-		DP_STR(GET_MSG_TRANSACTION_VERSION),
-		DP_STR(LINK_ADDRESS),
-		DP_STR(CONNECTION_STATUS_NOTIFY),
-		DP_STR(ENUM_PATH_RESOURCES),
-		DP_STR(ALLOCATE_PAYLOAD),
-		DP_STR(QUERY_PAYLOAD),
-		DP_STR(RESOURCE_STATUS_NOTIFY),
-		DP_STR(CLEAR_PAYLOAD_ID_TABLE),
-		DP_STR(REMOTE_DPCD_READ),
-		DP_STR(REMOTE_DPCD_WRITE),
-		DP_STR(REMOTE_I2C_READ),
-		DP_STR(REMOTE_I2C_WRITE),
-		DP_STR(POWER_UP_PHY),
-		DP_STR(POWER_DOWN_PHY),
-		DP_STR(SINK_EVENT_NOTIFY),
-		DP_STR(QUERY_STREAM_ENC_STATUS),
-	};
-
-	if (req_type >= ARRAY_SIZE(req_type_str) ||
-	    !req_type_str[req_type])
-		return "unknown";
-
-	return req_type_str[req_type];
-}
-
-#undef DP_STR
-#define DP_STR(x) [DP_NAK_ ## x] = #x
-
-static const char *drm_dp_mst_nak_reason_str(u8 nak_reason)
-{
-	static const char * const nak_reason_str[] = {
-		DP_STR(WRITE_FAILURE),
-		DP_STR(INVALID_READ),
-		DP_STR(CRC_FAILURE),
-		DP_STR(BAD_PARAM),
-		DP_STR(DEFER),
-		DP_STR(LINK_FAILURE),
-		DP_STR(NO_RESOURCES),
-		DP_STR(DPCD_FAIL),
-		DP_STR(I2C_NAK),
-		DP_STR(ALLOCATE_FAIL),
-	};
-
-	if (nak_reason >= ARRAY_SIZE(nak_reason_str) ||
-	    !nak_reason_str[nak_reason])
-		return "unknown";
-
-	return nak_reason_str[nak_reason];
-}
-
-#undef DP_STR
-#define DP_STR(x) [DRM_DP_SIDEBAND_TX_ ## x] = #x
-
-static const char *drm_dp_mst_sideband_tx_state_str(int state)
-{
-	static const char * const sideband_reason_str[] = {
-		DP_STR(QUEUED),
-		DP_STR(START_SEND),
-		DP_STR(SENT),
-		DP_STR(RX),
-		DP_STR(TIMEOUT),
-	};
-
-	if (state >= ARRAY_SIZE(sideband_reason_str) ||
-	    !sideband_reason_str[state])
-		return "unknown";
-
-	return sideband_reason_str[state];
-}
-
-static int
-drm_dp_mst_rad_to_str(const u8 rad[8], u8 lct, char *out, size_t len)
-{
-	int i;
-	u8 unpacked_rad[16];
-
-	for (i = 0; i < lct; i++) {
-		if (i % 2)
-			unpacked_rad[i] = rad[i / 2] >> 4;
-		else
-			unpacked_rad[i] = rad[i / 2] & BIT_MASK(4);
-	}
-
-	/* TODO: Eventually add something to printk so we can format the rad
-	 * like this: 1.2.3
-	 */
-	return snprintf(out, len, "%*phC", lct, unpacked_rad);
-}
-
-/* sideband msg handling */
-static u8 drm_dp_msg_header_crc4(const uint8_t *data, size_t num_nibbles)
-{
-	u8 bitmask = 0x80;
-	u8 bitshift = 7;
-	u8 array_index = 0;
-	int number_of_bits = num_nibbles * 4;
-	u8 remainder = 0;
-
-	while (number_of_bits != 0) {
-		number_of_bits--;
-		remainder <<= 1;
-		remainder |= (data[array_index] & bitmask) >> bitshift;
-		bitmask >>= 1;
-		bitshift--;
-		if (bitmask == 0) {
-			bitmask = 0x80;
-			bitshift = 7;
-			array_index++;
-		}
-		if ((remainder & 0x10) == 0x10)
-			remainder ^= 0x13;
-	}
-
-	number_of_bits = 4;
-	while (number_of_bits != 0) {
-		number_of_bits--;
-		remainder <<= 1;
-		if ((remainder & 0x10) != 0)
-			remainder ^= 0x13;
-	}
-
-	return remainder;
-}
-
-static u8 drm_dp_msg_data_crc4(const uint8_t *data, u8 number_of_bytes)
-{
-	u8 bitmask = 0x80;
-	u8 bitshift = 7;
-	u8 array_index = 0;
-	int number_of_bits = number_of_bytes * 8;
-	u16 remainder = 0;
-
-	while (number_of_bits != 0) {
-		number_of_bits--;
-		remainder <<= 1;
-		remainder |= (data[array_index] & bitmask) >> bitshift;
-		bitmask >>= 1;
-		bitshift--;
-		if (bitmask == 0) {
-			bitmask = 0x80;
-			bitshift = 7;
-			array_index++;
-		}
-		if ((remainder & 0x100) == 0x100)
-			remainder ^= 0xd5;
-	}
-
-	number_of_bits = 8;
-	while (number_of_bits != 0) {
-		number_of_bits--;
-		remainder <<= 1;
-		if ((remainder & 0x100) != 0)
-			remainder ^= 0xd5;
-	}
-
-	return remainder & 0xff;
-}
-static inline u8 drm_dp_calc_sb_hdr_size(struct drm_dp_sideband_msg_hdr *hdr)
-{
-	u8 size = 3;
-
-	size += (hdr->lct / 2);
-	return size;
-}
-
-static void drm_dp_encode_sideband_msg_hdr(struct drm_dp_sideband_msg_hdr *hdr,
-					   u8 *buf, int *len)
-{
-	int idx = 0;
-	int i;
-	u8 crc4;
-
-	buf[idx++] = ((hdr->lct & 0xf) << 4) | (hdr->lcr & 0xf);
-	for (i = 0; i < (hdr->lct / 2); i++)
-		buf[idx++] = hdr->rad[i];
-	buf[idx++] = (hdr->broadcast << 7) | (hdr->path_msg << 6) |
-		(hdr->msg_len & 0x3f);
-	buf[idx++] = (hdr->somt << 7) | (hdr->eomt << 6) | (hdr->seqno << 4);
-
-	crc4 = drm_dp_msg_header_crc4(buf, (idx * 2) - 1);
-	buf[idx - 1] |= (crc4 & 0xf);
-
-	*len = idx;
-}
-
-static bool drm_dp_decode_sideband_msg_hdr(const struct drm_dp_mst_topology_mgr *mgr,
-					   struct drm_dp_sideband_msg_hdr *hdr,
-					   u8 *buf, int buflen, u8 *hdrlen)
-{
-	u8 crc4;
-	u8 len;
-	int i;
-	u8 idx;
-
-	if (buf[0] == 0)
-		return false;
-	len = 3;
-	len += ((buf[0] & 0xf0) >> 4) / 2;
-	if (len > buflen)
-		return false;
-	crc4 = drm_dp_msg_header_crc4(buf, (len * 2) - 1);
-
-	if ((crc4 & 0xf) != (buf[len - 1] & 0xf)) {
-		drm_dbg_kms(mgr->dev, "crc4 mismatch 0x%x 0x%x\n", crc4, buf[len - 1]);
-		return false;
-	}
-
-	hdr->lct = (buf[0] & 0xf0) >> 4;
-	hdr->lcr = (buf[0] & 0xf);
-	idx = 1;
-	for (i = 0; i < (hdr->lct / 2); i++)
-		hdr->rad[i] = buf[idx++];
-	hdr->broadcast = (buf[idx] >> 7) & 0x1;
-	hdr->path_msg = (buf[idx] >> 6) & 0x1;
-	hdr->msg_len = buf[idx] & 0x3f;
-	idx++;
-	hdr->somt = (buf[idx] >> 7) & 0x1;
-	hdr->eomt = (buf[idx] >> 6) & 0x1;
-	hdr->seqno = (buf[idx] >> 4) & 0x1;
-	idx++;
-	*hdrlen = idx;
-	return true;
-}
-
-void
-drm_dp_encode_sideband_req(const struct drm_dp_sideband_msg_req_body *req,
-			   struct drm_dp_sideband_msg_tx *raw)
-{
-	int idx = 0;
-	int i;
-	u8 *buf = raw->msg;
-
-	buf[idx++] = req->req_type & 0x7f;
-
-	switch (req->req_type) {
-	case DP_ENUM_PATH_RESOURCES:
-	case DP_POWER_DOWN_PHY:
-	case DP_POWER_UP_PHY:
-		buf[idx] = (req->u.port_num.port_number & 0xf) << 4;
-		idx++;
-		break;
-	case DP_ALLOCATE_PAYLOAD:
-		buf[idx] = (req->u.allocate_payload.port_number & 0xf) << 4 |
-			(req->u.allocate_payload.number_sdp_streams & 0xf);
-		idx++;
-		buf[idx] = (req->u.allocate_payload.vcpi & 0x7f);
-		idx++;
-		buf[idx] = (req->u.allocate_payload.pbn >> 8);
-		idx++;
-		buf[idx] = (req->u.allocate_payload.pbn & 0xff);
-		idx++;
-		for (i = 0; i < req->u.allocate_payload.number_sdp_streams / 2; i++) {
-			buf[idx] = ((req->u.allocate_payload.sdp_stream_sink[i * 2] & 0xf) << 4) |
-				(req->u.allocate_payload.sdp_stream_sink[i * 2 + 1] & 0xf);
-			idx++;
-		}
-		if (req->u.allocate_payload.number_sdp_streams & 1) {
-			i = req->u.allocate_payload.number_sdp_streams - 1;
-			buf[idx] = (req->u.allocate_payload.sdp_stream_sink[i] & 0xf) << 4;
-			idx++;
-		}
-		break;
-	case DP_QUERY_PAYLOAD:
-		buf[idx] = (req->u.query_payload.port_number & 0xf) << 4;
-		idx++;
-		buf[idx] = (req->u.query_payload.vcpi & 0x7f);
-		idx++;
-		break;
-	case DP_REMOTE_DPCD_READ:
-		buf[idx] = (req->u.dpcd_read.port_number & 0xf) << 4;
-		buf[idx] |= ((req->u.dpcd_read.dpcd_address & 0xf0000) >> 16) & 0xf;
-		idx++;
-		buf[idx] = (req->u.dpcd_read.dpcd_address & 0xff00) >> 8;
-		idx++;
-		buf[idx] = (req->u.dpcd_read.dpcd_address & 0xff);
-		idx++;
-		buf[idx] = (req->u.dpcd_read.num_bytes);
-		idx++;
-		break;
-
-	case DP_REMOTE_DPCD_WRITE:
-		buf[idx] = (req->u.dpcd_write.port_number & 0xf) << 4;
-		buf[idx] |= ((req->u.dpcd_write.dpcd_address & 0xf0000) >> 16) & 0xf;
-		idx++;
-		buf[idx] = (req->u.dpcd_write.dpcd_address & 0xff00) >> 8;
-		idx++;
-		buf[idx] = (req->u.dpcd_write.dpcd_address & 0xff);
-		idx++;
-		buf[idx] = (req->u.dpcd_write.num_bytes);
-		idx++;
-		memcpy(&buf[idx], req->u.dpcd_write.bytes, req->u.dpcd_write.num_bytes);
-		idx += req->u.dpcd_write.num_bytes;
-		break;
-	case DP_REMOTE_I2C_READ:
-		buf[idx] = (req->u.i2c_read.port_number & 0xf) << 4;
-		buf[idx] |= (req->u.i2c_read.num_transactions & 0x3);
-		idx++;
-		for (i = 0; i < (req->u.i2c_read.num_transactions & 0x3); i++) {
-			buf[idx] = req->u.i2c_read.transactions[i].i2c_dev_id & 0x7f;
-			idx++;
-			buf[idx] = req->u.i2c_read.transactions[i].num_bytes;
-			idx++;
-			memcpy(&buf[idx], req->u.i2c_read.transactions[i].bytes, req->u.i2c_read.transactions[i].num_bytes);
-			idx += req->u.i2c_read.transactions[i].num_bytes;
-
-			buf[idx] = (req->u.i2c_read.transactions[i].no_stop_bit & 0x1) << 4;
-			buf[idx] |= (req->u.i2c_read.transactions[i].i2c_transaction_delay & 0xf);
-			idx++;
-		}
-		buf[idx] = (req->u.i2c_read.read_i2c_device_id) & 0x7f;
-		idx++;
-		buf[idx] = (req->u.i2c_read.num_bytes_read);
-		idx++;
-		break;
-
-	case DP_REMOTE_I2C_WRITE:
-		buf[idx] = (req->u.i2c_write.port_number & 0xf) << 4;
-		idx++;
-		buf[idx] = (req->u.i2c_write.write_i2c_device_id) & 0x7f;
-		idx++;
-		buf[idx] = (req->u.i2c_write.num_bytes);
-		idx++;
-		memcpy(&buf[idx], req->u.i2c_write.bytes, req->u.i2c_write.num_bytes);
-		idx += req->u.i2c_write.num_bytes;
-		break;
-	case DP_QUERY_STREAM_ENC_STATUS: {
-		const struct drm_dp_query_stream_enc_status *msg;
-
-		msg = &req->u.enc_status;
-		buf[idx] = msg->stream_id;
-		idx++;
-		memcpy(&buf[idx], msg->client_id, sizeof(msg->client_id));
-		idx += sizeof(msg->client_id);
-		buf[idx] = 0;
-		buf[idx] |= FIELD_PREP(GENMASK(1, 0), msg->stream_event);
-		buf[idx] |= msg->valid_stream_event ? BIT(2) : 0;
-		buf[idx] |= FIELD_PREP(GENMASK(4, 3), msg->stream_behavior);
-		buf[idx] |= msg->valid_stream_behavior ? BIT(5) : 0;
-		idx++;
-		}
-		break;
-	}
-	raw->cur_len = idx;
-}
-EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_encode_sideband_req);
-
-/* Decode a sideband request we've encoded, mainly used for debugging */
-int
-drm_dp_decode_sideband_req(const struct drm_dp_sideband_msg_tx *raw,
-			   struct drm_dp_sideband_msg_req_body *req)
-{
-	const u8 *buf = raw->msg;
-	int i, idx = 0;
-
-	req->req_type = buf[idx++] & 0x7f;
-	switch (req->req_type) {
-	case DP_ENUM_PATH_RESOURCES:
-	case DP_POWER_DOWN_PHY:
-	case DP_POWER_UP_PHY:
-		req->u.port_num.port_number = (buf[idx] >> 4) & 0xf;
-		break;
-	case DP_ALLOCATE_PAYLOAD:
-		{
-			struct drm_dp_allocate_payload *a =
-				&req->u.allocate_payload;
-
-			a->number_sdp_streams = buf[idx] & 0xf;
-			a->port_number = (buf[idx] >> 4) & 0xf;
-
-			WARN_ON(buf[++idx] & 0x80);
-			a->vcpi = buf[idx] & 0x7f;
-
-			a->pbn = buf[++idx] << 8;
-			a->pbn |= buf[++idx];
-
-			idx++;
-			for (i = 0; i < a->number_sdp_streams; i++) {
-				a->sdp_stream_sink[i] =
-					(buf[idx + (i / 2)] >> ((i % 2) ? 0 : 4)) & 0xf;
-			}
-		}
-		break;
-	case DP_QUERY_PAYLOAD:
-		req->u.query_payload.port_number = (buf[idx] >> 4) & 0xf;
-		WARN_ON(buf[++idx] & 0x80);
-		req->u.query_payload.vcpi = buf[idx] & 0x7f;
-		break;
-	case DP_REMOTE_DPCD_READ:
-		{
-			struct drm_dp_remote_dpcd_read *r = &req->u.dpcd_read;
-
-			r->port_number = (buf[idx] >> 4) & 0xf;
-
-			r->dpcd_address = (buf[idx] << 16) & 0xf0000;
-			r->dpcd_address |= (buf[++idx] << 8) & 0xff00;
-			r->dpcd_address |= buf[++idx] & 0xff;
-
-			r->num_bytes = buf[++idx];
-		}
-		break;
-	case DP_REMOTE_DPCD_WRITE:
-		{
-			struct drm_dp_remote_dpcd_write *w =
-				&req->u.dpcd_write;
-
-			w->port_number = (buf[idx] >> 4) & 0xf;
-
-			w->dpcd_address = (buf[idx] << 16) & 0xf0000;
-			w->dpcd_address |= (buf[++idx] << 8) & 0xff00;
-			w->dpcd_address |= buf[++idx] & 0xff;
-
-			w->num_bytes = buf[++idx];
-
-			w->bytes = kmemdup(&buf[++idx], w->num_bytes,
-					   GFP_KERNEL);
-			if (!w->bytes)
-				return -ENOMEM;
-		}
-		break;
-	case DP_REMOTE_I2C_READ:
-		{
-			struct drm_dp_remote_i2c_read *r = &req->u.i2c_read;
-			struct drm_dp_remote_i2c_read_tx *tx;
-			bool failed = false;
-
-			r->num_transactions = buf[idx] & 0x3;
-			r->port_number = (buf[idx] >> 4) & 0xf;
-			for (i = 0; i < r->num_transactions; i++) {
-				tx = &r->transactions[i];
-
-				tx->i2c_dev_id = buf[++idx] & 0x7f;
-				tx->num_bytes = buf[++idx];
-				tx->bytes = kmemdup(&buf[++idx],
-						    tx->num_bytes,
-						    GFP_KERNEL);
-				if (!tx->bytes) {
-					failed = true;
-					break;
-				}
-				idx += tx->num_bytes;
-				tx->no_stop_bit = (buf[idx] >> 5) & 0x1;
-				tx->i2c_transaction_delay = buf[idx] & 0xf;
-			}
-
-			if (failed) {
-				for (i = 0; i < r->num_transactions; i++) {
-					tx = &r->transactions[i];
-					kfree(tx->bytes);
-				}
-				return -ENOMEM;
-			}
-
-			r->read_i2c_device_id = buf[++idx] & 0x7f;
-			r->num_bytes_read = buf[++idx];
-		}
-		break;
-	case DP_REMOTE_I2C_WRITE:
-		{
-			struct drm_dp_remote_i2c_write *w = &req->u.i2c_write;
-
-			w->port_number = (buf[idx] >> 4) & 0xf;
-			w->write_i2c_device_id = buf[++idx] & 0x7f;
-			w->num_bytes = buf[++idx];
-			w->bytes = kmemdup(&buf[++idx], w->num_bytes,
-					   GFP_KERNEL);
-			if (!w->bytes)
-				return -ENOMEM;
-		}
-		break;
-	case DP_QUERY_STREAM_ENC_STATUS:
-		req->u.enc_status.stream_id = buf[idx++];
-		for (i = 0; i < sizeof(req->u.enc_status.client_id); i++)
-			req->u.enc_status.client_id[i] = buf[idx++];
-
-		req->u.enc_status.stream_event = FIELD_GET(GENMASK(1, 0),
-							   buf[idx]);
-		req->u.enc_status.valid_stream_event = FIELD_GET(BIT(2),
-								 buf[idx]);
-		req->u.enc_status.stream_behavior = FIELD_GET(GENMASK(4, 3),
-							      buf[idx]);
-		req->u.enc_status.valid_stream_behavior = FIELD_GET(BIT(5),
-								    buf[idx]);
-		break;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_decode_sideband_req);
-
-void
-drm_dp_dump_sideband_msg_req_body(const struct drm_dp_sideband_msg_req_body *req,
-				  int indent, struct drm_printer *printer)
-{
-	int i;
-
-#define P(f, ...) drm_printf_indent(printer, indent, f, ##__VA_ARGS__)
-	if (req->req_type == DP_LINK_ADDRESS) {
-		/* No contents to print */
-		P("type=%s\n", drm_dp_mst_req_type_str(req->req_type));
-		return;
-	}
-
-	P("type=%s contents:\n", drm_dp_mst_req_type_str(req->req_type));
-	indent++;
-
-	switch (req->req_type) {
-	case DP_ENUM_PATH_RESOURCES:
-	case DP_POWER_DOWN_PHY:
-	case DP_POWER_UP_PHY:
-		P("port=%d\n", req->u.port_num.port_number);
-		break;
-	case DP_ALLOCATE_PAYLOAD:
-		P("port=%d vcpi=%d pbn=%d sdp_streams=%d %*ph\n",
-		  req->u.allocate_payload.port_number,
-		  req->u.allocate_payload.vcpi, req->u.allocate_payload.pbn,
-		  req->u.allocate_payload.number_sdp_streams,
-		  req->u.allocate_payload.number_sdp_streams,
-		  req->u.allocate_payload.sdp_stream_sink);
-		break;
-	case DP_QUERY_PAYLOAD:
-		P("port=%d vcpi=%d\n",
-		  req->u.query_payload.port_number,
-		  req->u.query_payload.vcpi);
-		break;
-	case DP_REMOTE_DPCD_READ:
-		P("port=%d dpcd_addr=%05x len=%d\n",
-		  req->u.dpcd_read.port_number, req->u.dpcd_read.dpcd_address,
-		  req->u.dpcd_read.num_bytes);
-		break;
-	case DP_REMOTE_DPCD_WRITE:
-		P("port=%d addr=%05x len=%d: %*ph\n",
-		  req->u.dpcd_write.port_number,
-		  req->u.dpcd_write.dpcd_address,
-		  req->u.dpcd_write.num_bytes, req->u.dpcd_write.num_bytes,
-		  req->u.dpcd_write.bytes);
-		break;
-	case DP_REMOTE_I2C_READ:
-		P("port=%d num_tx=%d id=%d size=%d:\n",
-		  req->u.i2c_read.port_number,
-		  req->u.i2c_read.num_transactions,
-		  req->u.i2c_read.read_i2c_device_id,
-		  req->u.i2c_read.num_bytes_read);
-
-		indent++;
-		for (i = 0; i < req->u.i2c_read.num_transactions; i++) {
-			const struct drm_dp_remote_i2c_read_tx *rtx =
-				&req->u.i2c_read.transactions[i];
-
-			P("%d: id=%03d size=%03d no_stop_bit=%d tx_delay=%03d: %*ph\n",
-			  i, rtx->i2c_dev_id, rtx->num_bytes,
-			  rtx->no_stop_bit, rtx->i2c_transaction_delay,
-			  rtx->num_bytes, rtx->bytes);
-		}
-		break;
-	case DP_REMOTE_I2C_WRITE:
-		P("port=%d id=%d size=%d: %*ph\n",
-		  req->u.i2c_write.port_number,
-		  req->u.i2c_write.write_i2c_device_id,
-		  req->u.i2c_write.num_bytes, req->u.i2c_write.num_bytes,
-		  req->u.i2c_write.bytes);
-		break;
-	case DP_QUERY_STREAM_ENC_STATUS:
-		P("stream_id=%u client_id=%*ph stream_event=%x "
-		  "valid_event=%d stream_behavior=%x valid_behavior=%d",
-		  req->u.enc_status.stream_id,
-		  (int)ARRAY_SIZE(req->u.enc_status.client_id),
-		  req->u.enc_status.client_id, req->u.enc_status.stream_event,
-		  req->u.enc_status.valid_stream_event,
-		  req->u.enc_status.stream_behavior,
-		  req->u.enc_status.valid_stream_behavior);
-		break;
-	default:
-		P("???\n");
-		break;
-	}
-#undef P
-}
-EXPORT_SYMBOL_FOR_TESTS_ONLY(drm_dp_dump_sideband_msg_req_body);
-
-static inline void
-drm_dp_mst_dump_sideband_msg_tx(struct drm_printer *p,
-				const struct drm_dp_sideband_msg_tx *txmsg)
-{
-	struct drm_dp_sideband_msg_req_body req;
-	char buf[64];
-	int ret;
-	int i;
-
-	drm_dp_mst_rad_to_str(txmsg->dst->rad, txmsg->dst->lct, buf,
-			      sizeof(buf));
-	drm_printf(p, "txmsg cur_offset=%x cur_len=%x seqno=%x state=%s path_msg=%d dst=%s\n",
-		   txmsg->cur_offset, txmsg->cur_len, txmsg->seqno,
-		   drm_dp_mst_sideband_tx_state_str(txmsg->state),
-		   txmsg->path_msg, buf);
-
-	ret = drm_dp_decode_sideband_req(txmsg, &req);
-	if (ret) {
-		drm_printf(p, "<failed to decode sideband req: %d>\n", ret);
-		return;
-	}
-	drm_dp_dump_sideband_msg_req_body(&req, 1, p);
-
-	switch (req.req_type) {
-	case DP_REMOTE_DPCD_WRITE:
-		kfree(req.u.dpcd_write.bytes);
-		break;
-	case DP_REMOTE_I2C_READ:
-		for (i = 0; i < req.u.i2c_read.num_transactions; i++)
-			kfree(req.u.i2c_read.transactions[i].bytes);
-		break;
-	case DP_REMOTE_I2C_WRITE:
-		kfree(req.u.i2c_write.bytes);
-		break;
-	}
-}
-
-static void drm_dp_crc_sideband_chunk_req(u8 *msg, u8 len)
-{
-	u8 crc4;
-
-	crc4 = drm_dp_msg_data_crc4(msg, len);
-	msg[len] = crc4;
-}
-
-static void drm_dp_encode_sideband_reply(struct drm_dp_sideband_msg_reply_body *rep,
-					 struct drm_dp_sideband_msg_tx *raw)
-{
-	int idx = 0;
-	u8 *buf = raw->msg;
-
-	buf[idx++] = (rep->reply_type & 0x1) << 7 | (rep->req_type & 0x7f);
-
-	raw->cur_len = idx;
-}
-
-static int drm_dp_sideband_msg_set_header(struct drm_dp_sideband_msg_rx *msg,
-					  struct drm_dp_sideband_msg_hdr *hdr,
-					  u8 hdrlen)
-{
-	/*
-	 * ignore out-of-order messages or messages that are part of a
-	 * failed transaction
-	 */
-	if (!hdr->somt && !msg->have_somt)
-		return false;
-
-	/* get length contained in this portion */
-	msg->curchunk_idx = 0;
-	msg->curchunk_len = hdr->msg_len;
-	msg->curchunk_hdrlen = hdrlen;
-
-	/* we have already gotten an somt - don't bother parsing */
-	if (hdr->somt && msg->have_somt)
-		return false;
-
-	if (hdr->somt) {
-		memcpy(&msg->initial_hdr, hdr,
-		       sizeof(struct drm_dp_sideband_msg_hdr));
-		msg->have_somt = true;
-	}
-	if (hdr->eomt)
-		msg->have_eomt = true;
-
-	return true;
-}
-
-/* this adds a chunk of msg to the builder to get the final msg */
-static bool drm_dp_sideband_append_payload(struct drm_dp_sideband_msg_rx *msg,
-					   u8 *replybuf, u8 replybuflen)
-{
-	u8 crc4;
-
-	memcpy(&msg->chunk[msg->curchunk_idx], replybuf, replybuflen);
-	msg->curchunk_idx += replybuflen;
-
-	if (msg->curchunk_idx >= msg->curchunk_len) {
-		/* do CRC */
-		crc4 = drm_dp_msg_data_crc4(msg->chunk, msg->curchunk_len - 1);
-		if (crc4 != msg->chunk[msg->curchunk_len - 1])
-			print_hex_dump(KERN_DEBUG, "wrong crc",
-				       DUMP_PREFIX_NONE, 16, 1,
-				       msg->chunk,  msg->curchunk_len, false);
-		/* copy chunk into bigger msg */
-		memcpy(&msg->msg[msg->curlen], msg->chunk, msg->curchunk_len - 1);
-		msg->curlen += msg->curchunk_len - 1;
-	}
-	return true;
-}
-
-static bool drm_dp_sideband_parse_link_address(const struct drm_dp_mst_topology_mgr *mgr,
-					       struct drm_dp_sideband_msg_rx *raw,
-					       struct drm_dp_sideband_msg_reply_body *repmsg)
-{
-	int idx = 1;
-	int i;
-
-	memcpy(repmsg->u.link_addr.guid, &raw->msg[idx], 16);
-	idx += 16;
-	repmsg->u.link_addr.nports = raw->msg[idx] & 0xf;
-	idx++;
-	if (idx > raw->curlen)
-		goto fail_len;
-	for (i = 0; i < repmsg->u.link_addr.nports; i++) {
-		if (raw->msg[idx] & 0x80)
-			repmsg->u.link_addr.ports[i].input_port = 1;
-
-		repmsg->u.link_addr.ports[i].peer_device_type = (raw->msg[idx] >> 4) & 0x7;
-		repmsg->u.link_addr.ports[i].port_number = (raw->msg[idx] & 0xf);
-
-		idx++;
-		if (idx > raw->curlen)
-			goto fail_len;
-		repmsg->u.link_addr.ports[i].mcs = (raw->msg[idx] >> 7) & 0x1;
-		repmsg->u.link_addr.ports[i].ddps = (raw->msg[idx] >> 6) & 0x1;
-		if (repmsg->u.link_addr.ports[i].input_port == 0)
-			repmsg->u.link_addr.ports[i].legacy_device_plug_status = (raw->msg[idx] >> 5) & 0x1;
-		idx++;
-		if (idx > raw->curlen)
-			goto fail_len;
-		if (repmsg->u.link_addr.ports[i].input_port == 0) {
-			repmsg->u.link_addr.ports[i].dpcd_revision = (raw->msg[idx]);
-			idx++;
-			if (idx > raw->curlen)
-				goto fail_len;
-			memcpy(repmsg->u.link_addr.ports[i].peer_guid, &raw->msg[idx], 16);
-			idx += 16;
-			if (idx > raw->curlen)
-				goto fail_len;
-			repmsg->u.link_addr.ports[i].num_sdp_streams = (raw->msg[idx] >> 4) & 0xf;
-			repmsg->u.link_addr.ports[i].num_sdp_stream_sinks = (raw->msg[idx] & 0xf);
-			idx++;
-
-		}
-		if (idx > raw->curlen)
-			goto fail_len;
-	}
-
-	return true;
-fail_len:
-	DRM_DEBUG_KMS("link address reply parse length fail %d %d\n", idx, raw->curlen);
-	return false;
-}
-
-static bool drm_dp_sideband_parse_remote_dpcd_read(struct drm_dp_sideband_msg_rx *raw,
-						   struct drm_dp_sideband_msg_reply_body *repmsg)
-{
-	int idx = 1;
-
-	repmsg->u.remote_dpcd_read_ack.port_number = raw->msg[idx] & 0xf;
-	idx++;
-	if (idx > raw->curlen)
-		goto fail_len;
-	repmsg->u.remote_dpcd_read_ack.num_bytes = raw->msg[idx];
-	idx++;
-	if (idx > raw->curlen)
-		goto fail_len;
-
-	memcpy(repmsg->u.remote_dpcd_read_ack.bytes, &raw->msg[idx], repmsg->u.remote_dpcd_read_ack.num_bytes);
-	return true;
-fail_len:
-	DRM_DEBUG_KMS("link address reply parse length fail %d %d\n", idx, raw->curlen);
-	return false;
-}
-
-static bool drm_dp_sideband_parse_remote_dpcd_write(struct drm_dp_sideband_msg_rx *raw,
-						      struct drm_dp_sideband_msg_reply_body *repmsg)
-{
-	int idx = 1;
-
-	repmsg->u.remote_dpcd_write_ack.port_number = raw->msg[idx] & 0xf;
-	idx++;
-	if (idx > raw->curlen)
-		goto fail_len;
-	return true;
-fail_len:
-	DRM_DEBUG_KMS("parse length fail %d %d\n", idx, raw->curlen);
-	return false;
-}
-
-static bool drm_dp_sideband_parse_remote_i2c_read_ack(struct drm_dp_sideband_msg_rx *raw,
-						      struct drm_dp_sideband_msg_reply_body *repmsg)
-{
-	int idx = 1;
-
-	repmsg->u.remote_i2c_read_ack.port_number = (raw->msg[idx] & 0xf);
-	idx++;
-	if (idx > raw->curlen)
-		goto fail_len;
-	repmsg->u.remote_i2c_read_ack.num_bytes = raw->msg[idx];
-	idx++;
-	/* TODO check */
-	memcpy(repmsg->u.remote_i2c_read_ack.bytes, &raw->msg[idx], repmsg->u.remote_i2c_read_ack.num_bytes);
-	return true;
-fail_len:
-	DRM_DEBUG_KMS("remote i2c reply parse length fail %d %d\n", idx, raw->curlen);
-	return false;
-}
-
-static bool drm_dp_sideband_parse_enum_path_resources_ack(struct drm_dp_sideband_msg_rx *raw,
-							  struct drm_dp_sideband_msg_reply_body *repmsg)
-{
-	int idx = 1;
-
-	repmsg->u.path_resources.port_number = (raw->msg[idx] >> 4) & 0xf;
-	repmsg->u.path_resources.fec_capable = raw->msg[idx] & 0x1;
-	idx++;
-	if (idx > raw->curlen)
-		goto fail_len;
-	repmsg->u.path_resources.full_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
-	idx += 2;
-	if (idx > raw->curlen)
-		goto fail_len;
-	repmsg->u.path_resources.avail_payload_bw_number = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
-	idx += 2;
-	if (idx > raw->curlen)
-		goto fail_len;
-	return true;
-fail_len:
-	DRM_DEBUG_KMS("enum resource parse length fail %d %d\n", idx, raw->curlen);
-	return false;
-}
-
-static bool drm_dp_sideband_parse_allocate_payload_ack(struct drm_dp_sideband_msg_rx *raw,
-							  struct drm_dp_sideband_msg_reply_body *repmsg)
-{
-	int idx = 1;
-
-	repmsg->u.allocate_payload.port_number = (raw->msg[idx] >> 4) & 0xf;
-	idx++;
-	if (idx > raw->curlen)
-		goto fail_len;
-	repmsg->u.allocate_payload.vcpi = raw->msg[idx];
-	idx++;
-	if (idx > raw->curlen)
-		goto fail_len;
-	repmsg->u.allocate_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx+1]);
-	idx += 2;
-	if (idx > raw->curlen)
-		goto fail_len;
-	return true;
-fail_len:
-	DRM_DEBUG_KMS("allocate payload parse length fail %d %d\n", idx, raw->curlen);
-	return false;
-}
-
-static bool drm_dp_sideband_parse_query_payload_ack(struct drm_dp_sideband_msg_rx *raw,
-						    struct drm_dp_sideband_msg_reply_body *repmsg)
-{
-	int idx = 1;
-
-	repmsg->u.query_payload.port_number = (raw->msg[idx] >> 4) & 0xf;
-	idx++;
-	if (idx > raw->curlen)
-		goto fail_len;
-	repmsg->u.query_payload.allocated_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
-	idx += 2;
-	if (idx > raw->curlen)
-		goto fail_len;
-	return true;
-fail_len:
-	DRM_DEBUG_KMS("query payload parse length fail %d %d\n", idx, raw->curlen);
-	return false;
-}
-
-static bool drm_dp_sideband_parse_power_updown_phy_ack(struct drm_dp_sideband_msg_rx *raw,
-						       struct drm_dp_sideband_msg_reply_body *repmsg)
-{
-	int idx = 1;
-
-	repmsg->u.port_number.port_number = (raw->msg[idx] >> 4) & 0xf;
-	idx++;
-	if (idx > raw->curlen) {
-		DRM_DEBUG_KMS("power up/down phy parse length fail %d %d\n",
-			      idx, raw->curlen);
-		return false;
-	}
-	return true;
-}
-
-static bool
-drm_dp_sideband_parse_query_stream_enc_status(
-				struct drm_dp_sideband_msg_rx *raw,
-				struct drm_dp_sideband_msg_reply_body *repmsg)
-{
-	struct drm_dp_query_stream_enc_status_ack_reply *reply;
-
-	reply = &repmsg->u.enc_status;
-
-	reply->stream_id = raw->msg[3];
-
-	reply->reply_signed = raw->msg[2] & BIT(0);
-
-	/*
-	 * NOTE: It's my impression from reading the spec that the below parsing
-	 * is correct. However I noticed while testing with an HDCP 1.4 display
-	 * through an HDCP 2.2 hub that only bit 3 was set. In that case, I
-	 * would expect both bits to be set. So keep the parsing following the
-	 * spec, but beware reality might not match the spec (at least for some
-	 * configurations).
-	 */
-	reply->hdcp_1x_device_present = raw->msg[2] & BIT(4);
-	reply->hdcp_2x_device_present = raw->msg[2] & BIT(3);
-
-	reply->query_capable_device_present = raw->msg[2] & BIT(5);
-	reply->legacy_device_present = raw->msg[2] & BIT(6);
-	reply->unauthorizable_device_present = raw->msg[2] & BIT(7);
-
-	reply->auth_completed = !!(raw->msg[1] & BIT(3));
-	reply->encryption_enabled = !!(raw->msg[1] & BIT(4));
-	reply->repeater_present = !!(raw->msg[1] & BIT(5));
-	reply->state = (raw->msg[1] & GENMASK(7, 6)) >> 6;
-
-	return true;
-}
-
-static bool drm_dp_sideband_parse_reply(const struct drm_dp_mst_topology_mgr *mgr,
-					struct drm_dp_sideband_msg_rx *raw,
-					struct drm_dp_sideband_msg_reply_body *msg)
-{
-	memset(msg, 0, sizeof(*msg));
-	msg->reply_type = (raw->msg[0] & 0x80) >> 7;
-	msg->req_type = (raw->msg[0] & 0x7f);
-
-	if (msg->reply_type == DP_SIDEBAND_REPLY_NAK) {
-		memcpy(msg->u.nak.guid, &raw->msg[1], 16);
-		msg->u.nak.reason = raw->msg[17];
-		msg->u.nak.nak_data = raw->msg[18];
-		return false;
-	}
-
-	switch (msg->req_type) {
-	case DP_LINK_ADDRESS:
-		return drm_dp_sideband_parse_link_address(mgr, raw, msg);
-	case DP_QUERY_PAYLOAD:
-		return drm_dp_sideband_parse_query_payload_ack(raw, msg);
-	case DP_REMOTE_DPCD_READ:
-		return drm_dp_sideband_parse_remote_dpcd_read(raw, msg);
-	case DP_REMOTE_DPCD_WRITE:
-		return drm_dp_sideband_parse_remote_dpcd_write(raw, msg);
-	case DP_REMOTE_I2C_READ:
-		return drm_dp_sideband_parse_remote_i2c_read_ack(raw, msg);
-	case DP_REMOTE_I2C_WRITE:
-		return true; /* since there's nothing to parse */
-	case DP_ENUM_PATH_RESOURCES:
-		return drm_dp_sideband_parse_enum_path_resources_ack(raw, msg);
-	case DP_ALLOCATE_PAYLOAD:
-		return drm_dp_sideband_parse_allocate_payload_ack(raw, msg);
-	case DP_POWER_DOWN_PHY:
-	case DP_POWER_UP_PHY:
-		return drm_dp_sideband_parse_power_updown_phy_ack(raw, msg);
-	case DP_CLEAR_PAYLOAD_ID_TABLE:
-		return true; /* since there's nothing to parse */
-	case DP_QUERY_STREAM_ENC_STATUS:
-		return drm_dp_sideband_parse_query_stream_enc_status(raw, msg);
-	default:
-		drm_err(mgr->dev, "Got unknown reply 0x%02x (%s)\n",
-			msg->req_type, drm_dp_mst_req_type_str(msg->req_type));
-		return false;
-	}
-}
-
-static bool
-drm_dp_sideband_parse_connection_status_notify(const struct drm_dp_mst_topology_mgr *mgr,
-					       struct drm_dp_sideband_msg_rx *raw,
-					       struct drm_dp_sideband_msg_req_body *msg)
-{
-	int idx = 1;
-
-	msg->u.conn_stat.port_number = (raw->msg[idx] & 0xf0) >> 4;
-	idx++;
-	if (idx > raw->curlen)
-		goto fail_len;
-
-	memcpy(msg->u.conn_stat.guid, &raw->msg[idx], 16);
-	idx += 16;
-	if (idx > raw->curlen)
-		goto fail_len;
-
-	msg->u.conn_stat.legacy_device_plug_status = (raw->msg[idx] >> 6) & 0x1;
-	msg->u.conn_stat.displayport_device_plug_status = (raw->msg[idx] >> 5) & 0x1;
-	msg->u.conn_stat.message_capability_status = (raw->msg[idx] >> 4) & 0x1;
-	msg->u.conn_stat.input_port = (raw->msg[idx] >> 3) & 0x1;
-	msg->u.conn_stat.peer_device_type = (raw->msg[idx] & 0x7);
-	idx++;
-	return true;
-fail_len:
-	drm_dbg_kms(mgr->dev, "connection status reply parse length fail %d %d\n",
-		    idx, raw->curlen);
-	return false;
-}
-
-static bool drm_dp_sideband_parse_resource_status_notify(const struct drm_dp_mst_topology_mgr *mgr,
-							 struct drm_dp_sideband_msg_rx *raw,
-							 struct drm_dp_sideband_msg_req_body *msg)
-{
-	int idx = 1;
-
-	msg->u.resource_stat.port_number = (raw->msg[idx] & 0xf0) >> 4;
-	idx++;
-	if (idx > raw->curlen)
-		goto fail_len;
-
-	memcpy(msg->u.resource_stat.guid, &raw->msg[idx], 16);
-	idx += 16;
-	if (idx > raw->curlen)
-		goto fail_len;
-
-	msg->u.resource_stat.available_pbn = (raw->msg[idx] << 8) | (raw->msg[idx + 1]);
-	idx++;
-	return true;
-fail_len:
-	drm_dbg_kms(mgr->dev, "resource status reply parse length fail %d %d\n", idx, raw->curlen);
-	return false;
-}
-
-static bool drm_dp_sideband_parse_req(const struct drm_dp_mst_topology_mgr *mgr,
-				      struct drm_dp_sideband_msg_rx *raw,
-				      struct drm_dp_sideband_msg_req_body *msg)
-{
-	memset(msg, 0, sizeof(*msg));
-	msg->req_type = (raw->msg[0] & 0x7f);
-
-	switch (msg->req_type) {
-	case DP_CONNECTION_STATUS_NOTIFY:
-		return drm_dp_sideband_parse_connection_status_notify(mgr, raw, msg);
-	case DP_RESOURCE_STATUS_NOTIFY:
-		return drm_dp_sideband_parse_resource_status_notify(mgr, raw, msg);
-	default:
-		drm_err(mgr->dev, "Got unknown request 0x%02x (%s)\n",
-			msg->req_type, drm_dp_mst_req_type_str(msg->req_type));
-		return false;
-	}
-}
-
-static void build_dpcd_write(struct drm_dp_sideband_msg_tx *msg,
-			     u8 port_num, u32 offset, u8 num_bytes, u8 *bytes)
-{
-	struct drm_dp_sideband_msg_req_body req;
-
-	req.req_type = DP_REMOTE_DPCD_WRITE;
-	req.u.dpcd_write.port_number = port_num;
-	req.u.dpcd_write.dpcd_address = offset;
-	req.u.dpcd_write.num_bytes = num_bytes;
-	req.u.dpcd_write.bytes = bytes;
-	drm_dp_encode_sideband_req(&req, msg);
-}
-
-static void build_link_address(struct drm_dp_sideband_msg_tx *msg)
-{
-	struct drm_dp_sideband_msg_req_body req;
-
-	req.req_type = DP_LINK_ADDRESS;
-	drm_dp_encode_sideband_req(&req, msg);
-}
-
-static void build_clear_payload_id_table(struct drm_dp_sideband_msg_tx *msg)
-{
-	struct drm_dp_sideband_msg_req_body req;
-
-	req.req_type = DP_CLEAR_PAYLOAD_ID_TABLE;
-	drm_dp_encode_sideband_req(&req, msg);
-	msg->path_msg = true;
-}
-
-static int build_enum_path_resources(struct drm_dp_sideband_msg_tx *msg,
-				     int port_num)
-{
-	struct drm_dp_sideband_msg_req_body req;
-
-	req.req_type = DP_ENUM_PATH_RESOURCES;
-	req.u.port_num.port_number = port_num;
-	drm_dp_encode_sideband_req(&req, msg);
-	msg->path_msg = true;
-	return 0;
-}
-
-static void build_allocate_payload(struct drm_dp_sideband_msg_tx *msg,
-				   int port_num,
-				   u8 vcpi, uint16_t pbn,
-				   u8 number_sdp_streams,
-				   u8 *sdp_stream_sink)
-{
-	struct drm_dp_sideband_msg_req_body req;
-
-	memset(&req, 0, sizeof(req));
-	req.req_type = DP_ALLOCATE_PAYLOAD;
-	req.u.allocate_payload.port_number = port_num;
-	req.u.allocate_payload.vcpi = vcpi;
-	req.u.allocate_payload.pbn = pbn;
-	req.u.allocate_payload.number_sdp_streams = number_sdp_streams;
-	memcpy(req.u.allocate_payload.sdp_stream_sink, sdp_stream_sink,
-		   number_sdp_streams);
-	drm_dp_encode_sideband_req(&req, msg);
-	msg->path_msg = true;
-}
-
-static void build_power_updown_phy(struct drm_dp_sideband_msg_tx *msg,
-				   int port_num, bool power_up)
-{
-	struct drm_dp_sideband_msg_req_body req;
-
-	if (power_up)
-		req.req_type = DP_POWER_UP_PHY;
-	else
-		req.req_type = DP_POWER_DOWN_PHY;
-
-	req.u.port_num.port_number = port_num;
-	drm_dp_encode_sideband_req(&req, msg);
-	msg->path_msg = true;
-}
-
-static int
-build_query_stream_enc_status(struct drm_dp_sideband_msg_tx *msg, u8 stream_id,
-			      u8 *q_id)
-{
-	struct drm_dp_sideband_msg_req_body req;
-
-	req.req_type = DP_QUERY_STREAM_ENC_STATUS;
-	req.u.enc_status.stream_id = stream_id;
-	memcpy(req.u.enc_status.client_id, q_id,
-	       sizeof(req.u.enc_status.client_id));
-	req.u.enc_status.stream_event = 0;
-	req.u.enc_status.valid_stream_event = false;
-	req.u.enc_status.stream_behavior = 0;
-	req.u.enc_status.valid_stream_behavior = false;
-
-	drm_dp_encode_sideband_req(&req, msg);
-	return 0;
-}
-
-static int drm_dp_mst_assign_payload_id(struct drm_dp_mst_topology_mgr *mgr,
-					struct drm_dp_vcpi *vcpi)
-{
-	int ret, vcpi_ret;
-
-	mutex_lock(&mgr->payload_lock);
-	ret = find_first_zero_bit(&mgr->payload_mask, mgr->max_payloads + 1);
-	if (ret > mgr->max_payloads) {
-		ret = -EINVAL;
-		drm_dbg_kms(mgr->dev, "out of payload ids %d\n", ret);
-		goto out_unlock;
-	}
-
-	vcpi_ret = find_first_zero_bit(&mgr->vcpi_mask, mgr->max_payloads + 1);
-	if (vcpi_ret > mgr->max_payloads) {
-		ret = -EINVAL;
-		drm_dbg_kms(mgr->dev, "out of vcpi ids %d\n", ret);
-		goto out_unlock;
-	}
-
-	set_bit(ret, &mgr->payload_mask);
-	set_bit(vcpi_ret, &mgr->vcpi_mask);
-	vcpi->vcpi = vcpi_ret + 1;
-	mgr->proposed_vcpis[ret - 1] = vcpi;
-out_unlock:
-	mutex_unlock(&mgr->payload_lock);
-	return ret;
-}
-
-static void drm_dp_mst_put_payload_id(struct drm_dp_mst_topology_mgr *mgr,
-				      int vcpi)
-{
-	int i;
-
-	if (vcpi == 0)
-		return;
-
-	mutex_lock(&mgr->payload_lock);
-	drm_dbg_kms(mgr->dev, "putting payload %d\n", vcpi);
-	clear_bit(vcpi - 1, &mgr->vcpi_mask);
-
-	for (i = 0; i < mgr->max_payloads; i++) {
-		if (mgr->proposed_vcpis[i] &&
-		    mgr->proposed_vcpis[i]->vcpi == vcpi) {
-			mgr->proposed_vcpis[i] = NULL;
-			clear_bit(i + 1, &mgr->payload_mask);
-		}
-	}
-	mutex_unlock(&mgr->payload_lock);
-}
-
-static bool check_txmsg_state(struct drm_dp_mst_topology_mgr *mgr,
-			      struct drm_dp_sideband_msg_tx *txmsg)
-{
-	unsigned int state;
-
-	/*
-	 * All updates to txmsg->state are protected by mgr->qlock, and the two
-	 * cases we check here are terminal states. For those the barriers
-	 * provided by the wake_up/wait_event pair are enough.
-	 */
-	state = READ_ONCE(txmsg->state);
-	return (state == DRM_DP_SIDEBAND_TX_RX ||
-		state == DRM_DP_SIDEBAND_TX_TIMEOUT);
-}
-
-static int drm_dp_mst_wait_tx_reply(struct drm_dp_mst_branch *mstb,
-				    struct drm_dp_sideband_msg_tx *txmsg)
-{
-	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
-	unsigned long wait_timeout = msecs_to_jiffies(4000);
-	unsigned long wait_expires = jiffies + wait_timeout;
-	int ret;
-
-	for (;;) {
-		/*
-		 * If the driver provides a way for this, change to
-		 * poll-waiting for the MST reply interrupt if we didn't receive
-		 * it for 50 msec. This would cater for cases where the HPD
-		 * pulse signal got lost somewhere, even though the sink raised
-		 * the corresponding MST interrupt correctly. One example is the
-		 * Club 3D CAC-1557 TypeC -> DP adapter which for some reason
-		 * filters out short pulses with a duration less than ~540 usec.
-		 *
-		 * The poll period is 50 msec to avoid missing an interrupt
-		 * after the sink has cleared it (after a 110msec timeout
-		 * since it raised the interrupt).
-		 */
-		ret = wait_event_timeout(mgr->tx_waitq,
-					 check_txmsg_state(mgr, txmsg),
-					 mgr->cbs->poll_hpd_irq ?
-						msecs_to_jiffies(50) :
-						wait_timeout);
-
-		if (ret || !mgr->cbs->poll_hpd_irq ||
-		    time_after(jiffies, wait_expires))
-			break;
-
-		mgr->cbs->poll_hpd_irq(mgr);
-	}
-
-	mutex_lock(&mgr->qlock);
-	if (ret > 0) {
-		if (txmsg->state == DRM_DP_SIDEBAND_TX_TIMEOUT) {
-			ret = -EIO;
-			goto out;
-		}
-	} else {
-		drm_dbg_kms(mgr->dev, "timedout msg send %p %d %d\n",
-			    txmsg, txmsg->state, txmsg->seqno);
-
-		/* dump some state */
-		ret = -EIO;
-
-		/* remove from q */
-		if (txmsg->state == DRM_DP_SIDEBAND_TX_QUEUED ||
-		    txmsg->state == DRM_DP_SIDEBAND_TX_START_SEND ||
-		    txmsg->state == DRM_DP_SIDEBAND_TX_SENT)
-			list_del(&txmsg->next);
-	}
-out:
-	if (unlikely(ret == -EIO) && drm_debug_enabled(DRM_UT_DP)) {
-		struct drm_printer p = drm_debug_printer(DBG_PREFIX);
-
-		drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
-	}
-	mutex_unlock(&mgr->qlock);
-
-	drm_dp_mst_kick_tx(mgr);
-	return ret;
-}
-
-static struct drm_dp_mst_branch *drm_dp_add_mst_branch_device(u8 lct, u8 *rad)
-{
-	struct drm_dp_mst_branch *mstb;
-
-	mstb = kzalloc(sizeof(*mstb), GFP_KERNEL);
-	if (!mstb)
-		return NULL;
-
-	mstb->lct = lct;
-	if (lct > 1)
-		memcpy(mstb->rad, rad, lct / 2);
-	INIT_LIST_HEAD(&mstb->ports);
-	kref_init(&mstb->topology_kref);
-	kref_init(&mstb->malloc_kref);
-	return mstb;
-}
-
-static void drm_dp_free_mst_branch_device(struct kref *kref)
-{
-	struct drm_dp_mst_branch *mstb =
-		container_of(kref, struct drm_dp_mst_branch, malloc_kref);
-
-	if (mstb->port_parent)
-		drm_dp_mst_put_port_malloc(mstb->port_parent);
-
-	kfree(mstb);
-}
-
-/**
- * DOC: Branch device and port refcounting
- *
- * Topology refcount overview
- * ~~~~~~~~~~~~~~~~~~~~~~~~~~
- *
- * The refcounting schemes for &struct drm_dp_mst_branch and &struct
- * drm_dp_mst_port are somewhat unusual. Both ports and branch devices have
- * two different kinds of refcounts: topology refcounts, and malloc refcounts.
- *
- * Topology refcounts are not exposed to drivers, and are handled internally
- * by the DP MST helpers. The helpers use them in order to prevent the
- * in-memory topology state from being changed in the middle of critical
- * operations like changing the internal state of payload allocations. This
- * means each branch and port will be considered to be connected to the rest
- * of the topology until its topology refcount reaches zero. Additionally,
- * for ports this means that their associated &struct drm_connector will stay
- * registered with userspace until the port's refcount reaches 0.
- *
- * Malloc refcount overview
- * ~~~~~~~~~~~~~~~~~~~~~~~~
- *
- * Malloc references are used to keep a &struct drm_dp_mst_port or &struct
- * drm_dp_mst_branch allocated even after all of its topology references have
- * been dropped, so that the driver or MST helpers can safely access each
- * branch's last known state before it was disconnected from the topology.
- * When the malloc refcount of a port or branch reaches 0, the memory
- * allocation containing the &struct drm_dp_mst_branch or &struct
- * drm_dp_mst_port respectively will be freed.
- *
- * For &struct drm_dp_mst_branch, malloc refcounts are not currently exposed
- * to drivers. As of writing this documentation, there are no drivers that
- * have a usecase for accessing &struct drm_dp_mst_branch outside of the MST
- * helpers. Exposing this API to drivers in a race-free manner would take more
- * tweaking of the refcounting scheme, however patches are welcome provided
- * there is a legitimate driver usecase for this.
- *
- * Refcount relationships in a topology
- * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- *
- * Let's take a look at why the relationship between topology and malloc
- * refcounts is designed the way it is.
- *
- * .. kernel-figure:: dp-mst/topology-figure-1.dot
- *
- *    An example of topology and malloc refs in a DP MST topology with two
- *    active payloads. Topology refcount increments are indicated by solid
- *    lines, and malloc refcount increments are indicated by dashed lines.
- *    Each starts from the branch which incremented the refcount, and ends at
- *    the branch to which the refcount belongs to, i.e. the arrow points the
- *    same way as the C pointers used to reference a structure.
- *
- * As you can see in the above figure, every branch increments the topology
- * refcount of its children, and increments the malloc refcount of its
- * parent. Additionally, every payload increments the malloc refcount of its
- * assigned port by 1.
- *
- * So, what would happen if MSTB #3 from the above figure was unplugged from
- * the system, but the driver hadn't yet removed payload #2 from port #3? The
- * topology would start to look like the figure below.
- *
- * .. kernel-figure:: dp-mst/topology-figure-2.dot
- *
- *    Ports and branch devices which have been released from memory are
- *    colored grey, and references which have been removed are colored red.
- *
- * Whenever a port or branch device's topology refcount reaches zero, it will
- * decrement the topology refcounts of all its children, the malloc refcount
- * of its parent, and finally its own malloc refcount. For MSTB #4 and port
- * #4, this means they both have been disconnected from the topology and freed
- * from memory. But, because payload #2 is still holding a reference to port
- * #3, port #3 is removed from the topology but its &struct drm_dp_mst_port
- * is still accessible from memory. This also means port #3 has not yet
- * decremented the malloc refcount of MSTB #3, so its &struct
- * drm_dp_mst_branch will also stay allocated in memory until port #3's
- * malloc refcount reaches 0.
- *
- * This relationship is necessary because in order to release payload #2, we
- * need to be able to figure out the last relative of port #3 that's still
- * connected to the topology. In this case, we would travel up the topology as
- * shown below.
- *
- * .. kernel-figure:: dp-mst/topology-figure-3.dot
- *
- * And finally, remove payload #2 by communicating with port #2 through
- * sideband transactions.
- */
-
-/**
- * drm_dp_mst_get_mstb_malloc() - Increment the malloc refcount of a branch
- * device
- * @mstb: The &struct drm_dp_mst_branch to increment the malloc refcount of
- *
- * Increments &drm_dp_mst_branch.malloc_kref. When
- * &drm_dp_mst_branch.malloc_kref reaches 0, the memory allocation for @mstb
- * will be released and @mstb may no longer be used.
- *
- * See also: drm_dp_mst_put_mstb_malloc()
- */
-static void
-drm_dp_mst_get_mstb_malloc(struct drm_dp_mst_branch *mstb)
-{
-	kref_get(&mstb->malloc_kref);
-	drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->malloc_kref));
-}
-
-/**
- * drm_dp_mst_put_mstb_malloc() - Decrement the malloc refcount of a branch
- * device
- * @mstb: The &struct drm_dp_mst_branch to decrement the malloc refcount of
- *
- * Decrements &drm_dp_mst_branch.malloc_kref. When
- * &drm_dp_mst_branch.malloc_kref reaches 0, the memory allocation for @mstb
- * will be released and @mstb may no longer be used.
- *
- * See also: drm_dp_mst_get_mstb_malloc()
- */
-static void
-drm_dp_mst_put_mstb_malloc(struct drm_dp_mst_branch *mstb)
-{
-	drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->malloc_kref) - 1);
-	kref_put(&mstb->malloc_kref, drm_dp_free_mst_branch_device);
-}
-
-static void drm_dp_free_mst_port(struct kref *kref)
-{
-	struct drm_dp_mst_port *port =
-		container_of(kref, struct drm_dp_mst_port, malloc_kref);
-
-	drm_dp_mst_put_mstb_malloc(port->parent);
-	kfree(port);
-}
-
-/**
- * drm_dp_mst_get_port_malloc() - Increment the malloc refcount of an MST port
- * @port: The &struct drm_dp_mst_port to increment the malloc refcount of
- *
- * Increments &drm_dp_mst_port.malloc_kref. When &drm_dp_mst_port.malloc_kref
- * reaches 0, the memory allocation for @port will be released and @port may
- * no longer be used.
- *
- * Because @port could potentially be freed at any time by the DP MST helpers
- * if &drm_dp_mst_port.malloc_kref reaches 0, including during a call to this
- * function, drivers that which to make use of &struct drm_dp_mst_port should
- * ensure that they grab at least one main malloc reference to their MST ports
- * in &drm_dp_mst_topology_cbs.add_connector. This callback is called before
- * there is any chance for &drm_dp_mst_port.malloc_kref to reach 0.
- *
- * See also: drm_dp_mst_put_port_malloc()
- */
-void
-drm_dp_mst_get_port_malloc(struct drm_dp_mst_port *port)
-{
-	kref_get(&port->malloc_kref);
-	drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->malloc_kref));
-}
-EXPORT_SYMBOL(drm_dp_mst_get_port_malloc);
-
-/**
- * drm_dp_mst_put_port_malloc() - Decrement the malloc refcount of an MST port
- * @port: The &struct drm_dp_mst_port to decrement the malloc refcount of
- *
- * Decrements &drm_dp_mst_port.malloc_kref. When &drm_dp_mst_port.malloc_kref
- * reaches 0, the memory allocation for @port will be released and @port may
- * no longer be used.
- *
- * See also: drm_dp_mst_get_port_malloc()
- */
-void
-drm_dp_mst_put_port_malloc(struct drm_dp_mst_port *port)
-{
-	drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->malloc_kref) - 1);
-	kref_put(&port->malloc_kref, drm_dp_free_mst_port);
-}
-EXPORT_SYMBOL(drm_dp_mst_put_port_malloc);
-
-#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
-
-#define STACK_DEPTH 8
-
-static noinline void
-__topology_ref_save(struct drm_dp_mst_topology_mgr *mgr,
-		    struct drm_dp_mst_topology_ref_history *history,
-		    enum drm_dp_mst_topology_ref_type type)
-{
-	struct drm_dp_mst_topology_ref_entry *entry = NULL;
-	depot_stack_handle_t backtrace;
-	ulong stack_entries[STACK_DEPTH];
-	uint n;
-	int i;
-
-	n = stack_trace_save(stack_entries, ARRAY_SIZE(stack_entries), 1);
-	backtrace = stack_depot_save(stack_entries, n, GFP_KERNEL);
-	if (!backtrace)
-		return;
-
-	/* Try to find an existing entry for this backtrace */
-	for (i = 0; i < history->len; i++) {
-		if (history->entries[i].backtrace == backtrace) {
-			entry = &history->entries[i];
-			break;
-		}
-	}
-
-	/* Otherwise add one */
-	if (!entry) {
-		struct drm_dp_mst_topology_ref_entry *new;
-		int new_len = history->len + 1;
-
-		new = krealloc(history->entries, sizeof(*new) * new_len,
-			       GFP_KERNEL);
-		if (!new)
-			return;
-
-		entry = &new[history->len];
-		history->len = new_len;
-		history->entries = new;
-
-		entry->backtrace = backtrace;
-		entry->type = type;
-		entry->count = 0;
-	}
-	entry->count++;
-	entry->ts_nsec = ktime_get_ns();
-}
-
-static int
-topology_ref_history_cmp(const void *a, const void *b)
-{
-	const struct drm_dp_mst_topology_ref_entry *entry_a = a, *entry_b = b;
-
-	if (entry_a->ts_nsec > entry_b->ts_nsec)
-		return 1;
-	else if (entry_a->ts_nsec < entry_b->ts_nsec)
-		return -1;
-	else
-		return 0;
-}
-
-static inline const char *
-topology_ref_type_to_str(enum drm_dp_mst_topology_ref_type type)
-{
-	if (type == DRM_DP_MST_TOPOLOGY_REF_GET)
-		return "get";
-	else
-		return "put";
-}
-
-static void
-__dump_topology_ref_history(struct drm_dp_mst_topology_ref_history *history,
-			    void *ptr, const char *type_str)
-{
-	struct drm_printer p = drm_debug_printer(DBG_PREFIX);
-	char *buf = kzalloc(PAGE_SIZE, GFP_KERNEL);
-	int i;
-
-	if (!buf)
-		return;
-
-	if (!history->len)
-		goto out;
-
-	/* First, sort the list so that it goes from oldest to newest
-	 * reference entry
-	 */
-	sort(history->entries, history->len, sizeof(*history->entries),
-	     topology_ref_history_cmp, NULL);
-
-	drm_printf(&p, "%s (%p) topology count reached 0, dumping history:\n",
-		   type_str, ptr);
-
-	for (i = 0; i < history->len; i++) {
-		const struct drm_dp_mst_topology_ref_entry *entry =
-			&history->entries[i];
-		u64 ts_nsec = entry->ts_nsec;
-		u32 rem_nsec = do_div(ts_nsec, 1000000000);
-
-		stack_depot_snprint(entry->backtrace, buf, PAGE_SIZE, 4);
-
-		drm_printf(&p, "  %d %ss (last at %5llu.%06u):\n%s",
-			   entry->count,
-			   topology_ref_type_to_str(entry->type),
-			   ts_nsec, rem_nsec / 1000, buf);
-	}
-
-	/* Now free the history, since this is the only time we expose it */
-	kfree(history->entries);
-out:
-	kfree(buf);
-}
-
-static __always_inline void
-drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb)
-{
-	__dump_topology_ref_history(&mstb->topology_ref_history, mstb,
-				    "MSTB");
-}
-
-static __always_inline void
-drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port)
-{
-	__dump_topology_ref_history(&port->topology_ref_history, port,
-				    "Port");
-}
-
-static __always_inline void
-save_mstb_topology_ref(struct drm_dp_mst_branch *mstb,
-		       enum drm_dp_mst_topology_ref_type type)
-{
-	__topology_ref_save(mstb->mgr, &mstb->topology_ref_history, type);
-}
-
-static __always_inline void
-save_port_topology_ref(struct drm_dp_mst_port *port,
-		       enum drm_dp_mst_topology_ref_type type)
-{
-	__topology_ref_save(port->mgr, &port->topology_ref_history, type);
-}
-
-static inline void
-topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr)
-{
-	mutex_lock(&mgr->topology_ref_history_lock);
-}
-
-static inline void
-topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr)
-{
-	mutex_unlock(&mgr->topology_ref_history_lock);
-}
-#else
-static inline void
-topology_ref_history_lock(struct drm_dp_mst_topology_mgr *mgr) {}
-static inline void
-topology_ref_history_unlock(struct drm_dp_mst_topology_mgr *mgr) {}
-static inline void
-drm_dp_mst_dump_mstb_topology_history(struct drm_dp_mst_branch *mstb) {}
-static inline void
-drm_dp_mst_dump_port_topology_history(struct drm_dp_mst_port *port) {}
-#define save_mstb_topology_ref(mstb, type)
-#define save_port_topology_ref(port, type)
-#endif
-
-static void drm_dp_destroy_mst_branch_device(struct kref *kref)
-{
-	struct drm_dp_mst_branch *mstb =
-		container_of(kref, struct drm_dp_mst_branch, topology_kref);
-	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
-
-	drm_dp_mst_dump_mstb_topology_history(mstb);
-
-	INIT_LIST_HEAD(&mstb->destroy_next);
-
-	/*
-	 * This can get called under mgr->mutex, so we need to perform the
-	 * actual destruction of the mstb in another worker
-	 */
-	mutex_lock(&mgr->delayed_destroy_lock);
-	list_add(&mstb->destroy_next, &mgr->destroy_branch_device_list);
-	mutex_unlock(&mgr->delayed_destroy_lock);
-	queue_work(mgr->delayed_destroy_wq, &mgr->delayed_destroy_work);
-}
-
-/**
- * drm_dp_mst_topology_try_get_mstb() - Increment the topology refcount of a
- * branch device unless it's zero
- * @mstb: &struct drm_dp_mst_branch to increment the topology refcount of
- *
- * Attempts to grab a topology reference to @mstb, if it hasn't yet been
- * removed from the topology (e.g. &drm_dp_mst_branch.topology_kref has
- * reached 0). Holding a topology reference implies that a malloc reference
- * will be held to @mstb as long as the user holds the topology reference.
- *
- * Care should be taken to ensure that the user has at least one malloc
- * reference to @mstb. If you already have a topology reference to @mstb, you
- * should use drm_dp_mst_topology_get_mstb() instead.
- *
- * See also:
- * drm_dp_mst_topology_get_mstb()
- * drm_dp_mst_topology_put_mstb()
- *
- * Returns:
- * * 1: A topology reference was grabbed successfully
- * * 0: @port is no longer in the topology, no reference was grabbed
- */
-static int __must_check
-drm_dp_mst_topology_try_get_mstb(struct drm_dp_mst_branch *mstb)
-{
-	int ret;
-
-	topology_ref_history_lock(mstb->mgr);
-	ret = kref_get_unless_zero(&mstb->topology_kref);
-	if (ret) {
-		drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->topology_kref));
-		save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET);
-	}
-
-	topology_ref_history_unlock(mstb->mgr);
-
-	return ret;
-}
-
-/**
- * drm_dp_mst_topology_get_mstb() - Increment the topology refcount of a
- * branch device
- * @mstb: The &struct drm_dp_mst_branch to increment the topology refcount of
- *
- * Increments &drm_dp_mst_branch.topology_refcount without checking whether or
- * not it's already reached 0. This is only valid to use in scenarios where
- * you are already guaranteed to have at least one active topology reference
- * to @mstb. Otherwise, drm_dp_mst_topology_try_get_mstb() must be used.
- *
- * See also:
- * drm_dp_mst_topology_try_get_mstb()
- * drm_dp_mst_topology_put_mstb()
- */
-static void drm_dp_mst_topology_get_mstb(struct drm_dp_mst_branch *mstb)
-{
-	topology_ref_history_lock(mstb->mgr);
-
-	save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_GET);
-	WARN_ON(kref_read(&mstb->topology_kref) == 0);
-	kref_get(&mstb->topology_kref);
-	drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->topology_kref));
-
-	topology_ref_history_unlock(mstb->mgr);
-}
-
-/**
- * drm_dp_mst_topology_put_mstb() - release a topology reference to a branch
- * device
- * @mstb: The &struct drm_dp_mst_branch to release the topology reference from
- *
- * Releases a topology reference from @mstb by decrementing
- * &drm_dp_mst_branch.topology_kref.
- *
- * See also:
- * drm_dp_mst_topology_try_get_mstb()
- * drm_dp_mst_topology_get_mstb()
- */
-static void
-drm_dp_mst_topology_put_mstb(struct drm_dp_mst_branch *mstb)
-{
-	topology_ref_history_lock(mstb->mgr);
-
-	drm_dbg(mstb->mgr->dev, "mstb %p (%d)\n", mstb, kref_read(&mstb->topology_kref) - 1);
-	save_mstb_topology_ref(mstb, DRM_DP_MST_TOPOLOGY_REF_PUT);
-
-	topology_ref_history_unlock(mstb->mgr);
-	kref_put(&mstb->topology_kref, drm_dp_destroy_mst_branch_device);
-}
-
-static void drm_dp_destroy_port(struct kref *kref)
-{
-	struct drm_dp_mst_port *port =
-		container_of(kref, struct drm_dp_mst_port, topology_kref);
-	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
-
-	drm_dp_mst_dump_port_topology_history(port);
-
-	/* There's nothing that needs locking to destroy an input port yet */
-	if (port->input) {
-		drm_dp_mst_put_port_malloc(port);
-		return;
-	}
-
-	kfree(port->cached_edid);
-
-	/*
-	 * we can't destroy the connector here, as we might be holding the
-	 * mode_config.mutex from an EDID retrieval
-	 */
-	mutex_lock(&mgr->delayed_destroy_lock);
-	list_add(&port->next, &mgr->destroy_port_list);
-	mutex_unlock(&mgr->delayed_destroy_lock);
-	queue_work(mgr->delayed_destroy_wq, &mgr->delayed_destroy_work);
-}
-
-/**
- * drm_dp_mst_topology_try_get_port() - Increment the topology refcount of a
- * port unless it's zero
- * @port: &struct drm_dp_mst_port to increment the topology refcount of
- *
- * Attempts to grab a topology reference to @port, if it hasn't yet been
- * removed from the topology (e.g. &drm_dp_mst_port.topology_kref has reached
- * 0). Holding a topology reference implies that a malloc reference will be
- * held to @port as long as the user holds the topology reference.
- *
- * Care should be taken to ensure that the user has at least one malloc
- * reference to @port. If you already have a topology reference to @port, you
- * should use drm_dp_mst_topology_get_port() instead.
- *
- * See also:
- * drm_dp_mst_topology_get_port()
- * drm_dp_mst_topology_put_port()
- *
- * Returns:
- * * 1: A topology reference was grabbed successfully
- * * 0: @port is no longer in the topology, no reference was grabbed
- */
-static int __must_check
-drm_dp_mst_topology_try_get_port(struct drm_dp_mst_port *port)
-{
-	int ret;
-
-	topology_ref_history_lock(port->mgr);
-	ret = kref_get_unless_zero(&port->topology_kref);
-	if (ret) {
-		drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->topology_kref));
-		save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET);
-	}
-
-	topology_ref_history_unlock(port->mgr);
-	return ret;
-}
-
-/**
- * drm_dp_mst_topology_get_port() - Increment the topology refcount of a port
- * @port: The &struct drm_dp_mst_port to increment the topology refcount of
- *
- * Increments &drm_dp_mst_port.topology_refcount without checking whether or
- * not it's already reached 0. This is only valid to use in scenarios where
- * you are already guaranteed to have at least one active topology reference
- * to @port. Otherwise, drm_dp_mst_topology_try_get_port() must be used.
- *
- * See also:
- * drm_dp_mst_topology_try_get_port()
- * drm_dp_mst_topology_put_port()
- */
-static void drm_dp_mst_topology_get_port(struct drm_dp_mst_port *port)
-{
-	topology_ref_history_lock(port->mgr);
-
-	WARN_ON(kref_read(&port->topology_kref) == 0);
-	kref_get(&port->topology_kref);
-	drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->topology_kref));
-	save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_GET);
-
-	topology_ref_history_unlock(port->mgr);
-}
-
-/**
- * drm_dp_mst_topology_put_port() - release a topology reference to a port
- * @port: The &struct drm_dp_mst_port to release the topology reference from
- *
- * Releases a topology reference from @port by decrementing
- * &drm_dp_mst_port.topology_kref.
- *
- * See also:
- * drm_dp_mst_topology_try_get_port()
- * drm_dp_mst_topology_get_port()
- */
-static void drm_dp_mst_topology_put_port(struct drm_dp_mst_port *port)
-{
-	topology_ref_history_lock(port->mgr);
-
-	drm_dbg(port->mgr->dev, "port %p (%d)\n", port, kref_read(&port->topology_kref) - 1);
-	save_port_topology_ref(port, DRM_DP_MST_TOPOLOGY_REF_PUT);
-
-	topology_ref_history_unlock(port->mgr);
-	kref_put(&port->topology_kref, drm_dp_destroy_port);
-}
-
-static struct drm_dp_mst_branch *
-drm_dp_mst_topology_get_mstb_validated_locked(struct drm_dp_mst_branch *mstb,
-					      struct drm_dp_mst_branch *to_find)
-{
-	struct drm_dp_mst_port *port;
-	struct drm_dp_mst_branch *rmstb;
-
-	if (to_find == mstb)
-		return mstb;
-
-	list_for_each_entry(port, &mstb->ports, next) {
-		if (port->mstb) {
-			rmstb = drm_dp_mst_topology_get_mstb_validated_locked(
-			    port->mstb, to_find);
-			if (rmstb)
-				return rmstb;
-		}
-	}
-	return NULL;
-}
-
-static struct drm_dp_mst_branch *
-drm_dp_mst_topology_get_mstb_validated(struct drm_dp_mst_topology_mgr *mgr,
-				       struct drm_dp_mst_branch *mstb)
-{
-	struct drm_dp_mst_branch *rmstb = NULL;
-
-	mutex_lock(&mgr->lock);
-	if (mgr->mst_primary) {
-		rmstb = drm_dp_mst_topology_get_mstb_validated_locked(
-		    mgr->mst_primary, mstb);
-
-		if (rmstb && !drm_dp_mst_topology_try_get_mstb(rmstb))
-			rmstb = NULL;
-	}
-	mutex_unlock(&mgr->lock);
-	return rmstb;
-}
-
-static struct drm_dp_mst_port *
-drm_dp_mst_topology_get_port_validated_locked(struct drm_dp_mst_branch *mstb,
-					      struct drm_dp_mst_port *to_find)
-{
-	struct drm_dp_mst_port *port, *mport;
-
-	list_for_each_entry(port, &mstb->ports, next) {
-		if (port == to_find)
-			return port;
-
-		if (port->mstb) {
-			mport = drm_dp_mst_topology_get_port_validated_locked(
-			    port->mstb, to_find);
-			if (mport)
-				return mport;
-		}
-	}
-	return NULL;
-}
-
-static struct drm_dp_mst_port *
-drm_dp_mst_topology_get_port_validated(struct drm_dp_mst_topology_mgr *mgr,
-				       struct drm_dp_mst_port *port)
-{
-	struct drm_dp_mst_port *rport = NULL;
-
-	mutex_lock(&mgr->lock);
-	if (mgr->mst_primary) {
-		rport = drm_dp_mst_topology_get_port_validated_locked(
-		    mgr->mst_primary, port);
-
-		if (rport && !drm_dp_mst_topology_try_get_port(rport))
-			rport = NULL;
-	}
-	mutex_unlock(&mgr->lock);
-	return rport;
-}
-
-static struct drm_dp_mst_port *drm_dp_get_port(struct drm_dp_mst_branch *mstb, u8 port_num)
-{
-	struct drm_dp_mst_port *port;
-	int ret;
-
-	list_for_each_entry(port, &mstb->ports, next) {
-		if (port->port_num == port_num) {
-			ret = drm_dp_mst_topology_try_get_port(port);
-			return ret ? port : NULL;
-		}
-	}
-
-	return NULL;
-}
-
-/*
- * calculate a new RAD for this MST branch device
- * if parent has an LCT of 2 then it has 1 nibble of RAD,
- * if parent has an LCT of 3 then it has 2 nibbles of RAD,
- */
-static u8 drm_dp_calculate_rad(struct drm_dp_mst_port *port,
-				 u8 *rad)
-{
-	int parent_lct = port->parent->lct;
-	int shift = 4;
-	int idx = (parent_lct - 1) / 2;
-
-	if (parent_lct > 1) {
-		memcpy(rad, port->parent->rad, idx + 1);
-		shift = (parent_lct % 2) ? 4 : 0;
-	} else
-		rad[0] = 0;
-
-	rad[idx] |= port->port_num << shift;
-	return parent_lct + 1;
-}
-
-static bool drm_dp_mst_is_end_device(u8 pdt, bool mcs)
-{
-	switch (pdt) {
-	case DP_PEER_DEVICE_DP_LEGACY_CONV:
-	case DP_PEER_DEVICE_SST_SINK:
-		return true;
-	case DP_PEER_DEVICE_MST_BRANCHING:
-		/* For sst branch device */
-		if (!mcs)
-			return true;
-
-		return false;
-	}
-	return true;
-}
-
-static int
-drm_dp_port_set_pdt(struct drm_dp_mst_port *port, u8 new_pdt,
-		    bool new_mcs)
-{
-	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
-	struct drm_dp_mst_branch *mstb;
-	u8 rad[8], lct;
-	int ret = 0;
-
-	if (port->pdt == new_pdt && port->mcs == new_mcs)
-		return 0;
-
-	/* Teardown the old pdt, if there is one */
-	if (port->pdt != DP_PEER_DEVICE_NONE) {
-		if (drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
-			/*
-			 * If the new PDT would also have an i2c bus,
-			 * don't bother with reregistering it
-			 */
-			if (new_pdt != DP_PEER_DEVICE_NONE &&
-			    drm_dp_mst_is_end_device(new_pdt, new_mcs)) {
-				port->pdt = new_pdt;
-				port->mcs = new_mcs;
-				return 0;
-			}
-
-			/* remove i2c over sideband */
-			drm_dp_mst_unregister_i2c_bus(port);
-		} else {
-			mutex_lock(&mgr->lock);
-			drm_dp_mst_topology_put_mstb(port->mstb);
-			port->mstb = NULL;
-			mutex_unlock(&mgr->lock);
-		}
-	}
-
-	port->pdt = new_pdt;
-	port->mcs = new_mcs;
-
-	if (port->pdt != DP_PEER_DEVICE_NONE) {
-		if (drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
-			/* add i2c over sideband */
-			ret = drm_dp_mst_register_i2c_bus(port);
-		} else {
-			lct = drm_dp_calculate_rad(port, rad);
-			mstb = drm_dp_add_mst_branch_device(lct, rad);
-			if (!mstb) {
-				ret = -ENOMEM;
-				drm_err(mgr->dev, "Failed to create MSTB for port %p", port);
-				goto out;
-			}
-
-			mutex_lock(&mgr->lock);
-			port->mstb = mstb;
-			mstb->mgr = port->mgr;
-			mstb->port_parent = port;
-
-			/*
-			 * Make sure this port's memory allocation stays
-			 * around until its child MSTB releases it
-			 */
-			drm_dp_mst_get_port_malloc(port);
-			mutex_unlock(&mgr->lock);
-
-			/* And make sure we send a link address for this */
-			ret = 1;
-		}
-	}
-
-out:
-	if (ret < 0)
-		port->pdt = DP_PEER_DEVICE_NONE;
-	return ret;
-}
-
-/**
- * drm_dp_mst_dpcd_read() - read a series of bytes from the DPCD via sideband
- * @aux: Fake sideband AUX CH
- * @offset: address of the (first) register to read
- * @buffer: buffer to store the register values
- * @size: number of bytes in @buffer
- *
- * Performs the same functionality for remote devices via
- * sideband messaging as drm_dp_dpcd_read() does for local
- * devices via actual AUX CH.
- *
- * Return: Number of bytes read, or negative error code on failure.
- */
-ssize_t drm_dp_mst_dpcd_read(struct drm_dp_aux *aux,
-			     unsigned int offset, void *buffer, size_t size)
-{
-	struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port,
-						    aux);
-
-	return drm_dp_send_dpcd_read(port->mgr, port,
-				     offset, size, buffer);
-}
-
-/**
- * drm_dp_mst_dpcd_write() - write a series of bytes to the DPCD via sideband
- * @aux: Fake sideband AUX CH
- * @offset: address of the (first) register to write
- * @buffer: buffer containing the values to write
- * @size: number of bytes in @buffer
- *
- * Performs the same functionality for remote devices via
- * sideband messaging as drm_dp_dpcd_write() does for local
- * devices via actual AUX CH.
- *
- * Return: number of bytes written on success, negative error code on failure.
- */
-ssize_t drm_dp_mst_dpcd_write(struct drm_dp_aux *aux,
-			      unsigned int offset, void *buffer, size_t size)
-{
-	struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port,
-						    aux);
-
-	return drm_dp_send_dpcd_write(port->mgr, port,
-				      offset, size, buffer);
-}
-
-static int drm_dp_check_mstb_guid(struct drm_dp_mst_branch *mstb, u8 *guid)
-{
-	int ret = 0;
-
-	memcpy(mstb->guid, guid, 16);
-
-	if (!drm_dp_validate_guid(mstb->mgr, mstb->guid)) {
-		if (mstb->port_parent) {
-			ret = drm_dp_send_dpcd_write(mstb->mgr,
-						     mstb->port_parent,
-						     DP_GUID, 16, mstb->guid);
-		} else {
-			ret = drm_dp_dpcd_write(mstb->mgr->aux,
-						DP_GUID, mstb->guid, 16);
-		}
-	}
-
-	if (ret < 16 && ret > 0)
-		return -EPROTO;
-
-	return ret == 16 ? 0 : ret;
-}
-
-static void build_mst_prop_path(const struct drm_dp_mst_branch *mstb,
-				int pnum,
-				char *proppath,
-				size_t proppath_size)
-{
-	int i;
-	char temp[8];
-
-	snprintf(proppath, proppath_size, "mst:%d", mstb->mgr->conn_base_id);
-	for (i = 0; i < (mstb->lct - 1); i++) {
-		int shift = (i % 2) ? 0 : 4;
-		int port_num = (mstb->rad[i / 2] >> shift) & 0xf;
-
-		snprintf(temp, sizeof(temp), "-%d", port_num);
-		strlcat(proppath, temp, proppath_size);
-	}
-	snprintf(temp, sizeof(temp), "-%d", pnum);
-	strlcat(proppath, temp, proppath_size);
-}
-
-/**
- * drm_dp_mst_connector_late_register() - Late MST connector registration
- * @connector: The MST connector
- * @port: The MST port for this connector
- *
- * Helper to register the remote aux device for this MST port. Drivers should
- * call this from their mst connector's late_register hook to enable MST aux
- * devices.
- *
- * Return: 0 on success, negative error code on failure.
- */
-int drm_dp_mst_connector_late_register(struct drm_connector *connector,
-				       struct drm_dp_mst_port *port)
-{
-	drm_dbg_kms(port->mgr->dev, "registering %s remote bus for %s\n",
-		    port->aux.name, connector->kdev->kobj.name);
-
-	port->aux.dev = connector->kdev;
-	return drm_dp_aux_register_devnode(&port->aux);
-}
-EXPORT_SYMBOL(drm_dp_mst_connector_late_register);
-
-/**
- * drm_dp_mst_connector_early_unregister() - Early MST connector unregistration
- * @connector: The MST connector
- * @port: The MST port for this connector
- *
- * Helper to unregister the remote aux device for this MST port, registered by
- * drm_dp_mst_connector_late_register(). Drivers should call this from their mst
- * connector's early_unregister hook.
- */
-void drm_dp_mst_connector_early_unregister(struct drm_connector *connector,
-					   struct drm_dp_mst_port *port)
-{
-	drm_dbg_kms(port->mgr->dev, "unregistering %s remote bus for %s\n",
-		    port->aux.name, connector->kdev->kobj.name);
-	drm_dp_aux_unregister_devnode(&port->aux);
-}
-EXPORT_SYMBOL(drm_dp_mst_connector_early_unregister);
-
-static void
-drm_dp_mst_port_add_connector(struct drm_dp_mst_branch *mstb,
-			      struct drm_dp_mst_port *port)
-{
-	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
-	char proppath[255];
-	int ret;
-
-	build_mst_prop_path(mstb, port->port_num, proppath, sizeof(proppath));
-	port->connector = mgr->cbs->add_connector(mgr, port, proppath);
-	if (!port->connector) {
-		ret = -ENOMEM;
-		goto error;
-	}
-
-	if (port->pdt != DP_PEER_DEVICE_NONE &&
-	    drm_dp_mst_is_end_device(port->pdt, port->mcs) &&
-	    port->port_num >= DP_MST_LOGICAL_PORT_0)
-		port->cached_edid = drm_get_edid(port->connector,
-						 &port->aux.ddc);
-
-	drm_connector_register(port->connector);
-	return;
-
-error:
-	drm_err(mgr->dev, "Failed to create connector for port %p: %d\n", port, ret);
-}
-
-/*
- * Drop a topology reference, and unlink the port from the in-memory topology
- * layout
- */
-static void
-drm_dp_mst_topology_unlink_port(struct drm_dp_mst_topology_mgr *mgr,
-				struct drm_dp_mst_port *port)
-{
-	mutex_lock(&mgr->lock);
-	port->parent->num_ports--;
-	list_del(&port->next);
-	mutex_unlock(&mgr->lock);
-	drm_dp_mst_topology_put_port(port);
-}
-
-static struct drm_dp_mst_port *
-drm_dp_mst_add_port(struct drm_device *dev,
-		    struct drm_dp_mst_topology_mgr *mgr,
-		    struct drm_dp_mst_branch *mstb, u8 port_number)
-{
-	struct drm_dp_mst_port *port = kzalloc(sizeof(*port), GFP_KERNEL);
-
-	if (!port)
-		return NULL;
-
-	kref_init(&port->topology_kref);
-	kref_init(&port->malloc_kref);
-	port->parent = mstb;
-	port->port_num = port_number;
-	port->mgr = mgr;
-	port->aux.name = "DPMST";
-	port->aux.dev = dev->dev;
-	port->aux.is_remote = true;
-
-	/* initialize the MST downstream port's AUX crc work queue */
-	port->aux.drm_dev = dev;
-	drm_dp_remote_aux_init(&port->aux);
-
-	/*
-	 * Make sure the memory allocation for our parent branch stays
-	 * around until our own memory allocation is released
-	 */
-	drm_dp_mst_get_mstb_malloc(mstb);
-
-	return port;
-}
-
-static int
-drm_dp_mst_handle_link_address_port(struct drm_dp_mst_branch *mstb,
-				    struct drm_device *dev,
-				    struct drm_dp_link_addr_reply_port *port_msg)
-{
-	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
-	struct drm_dp_mst_port *port;
-	int old_ddps = 0, ret;
-	u8 new_pdt = DP_PEER_DEVICE_NONE;
-	bool new_mcs = 0;
-	bool created = false, send_link_addr = false, changed = false;
-
-	port = drm_dp_get_port(mstb, port_msg->port_number);
-	if (!port) {
-		port = drm_dp_mst_add_port(dev, mgr, mstb,
-					   port_msg->port_number);
-		if (!port)
-			return -ENOMEM;
-		created = true;
-		changed = true;
-	} else if (!port->input && port_msg->input_port && port->connector) {
-		/* Since port->connector can't be changed here, we create a
-		 * new port if input_port changes from 0 to 1
-		 */
-		drm_dp_mst_topology_unlink_port(mgr, port);
-		drm_dp_mst_topology_put_port(port);
-		port = drm_dp_mst_add_port(dev, mgr, mstb,
-					   port_msg->port_number);
-		if (!port)
-			return -ENOMEM;
-		changed = true;
-		created = true;
-	} else if (port->input && !port_msg->input_port) {
-		changed = true;
-	} else if (port->connector) {
-		/* We're updating a port that's exposed to userspace, so do it
-		 * under lock
-		 */
-		drm_modeset_lock(&mgr->base.lock, NULL);
-
-		old_ddps = port->ddps;
-		changed = port->ddps != port_msg->ddps ||
-			(port->ddps &&
-			 (port->ldps != port_msg->legacy_device_plug_status ||
-			  port->dpcd_rev != port_msg->dpcd_revision ||
-			  port->mcs != port_msg->mcs ||
-			  port->pdt != port_msg->peer_device_type ||
-			  port->num_sdp_stream_sinks !=
-			  port_msg->num_sdp_stream_sinks));
-	}
-
-	port->input = port_msg->input_port;
-	if (!port->input)
-		new_pdt = port_msg->peer_device_type;
-	new_mcs = port_msg->mcs;
-	port->ddps = port_msg->ddps;
-	port->ldps = port_msg->legacy_device_plug_status;
-	port->dpcd_rev = port_msg->dpcd_revision;
-	port->num_sdp_streams = port_msg->num_sdp_streams;
-	port->num_sdp_stream_sinks = port_msg->num_sdp_stream_sinks;
-
-	/* manage mstb port lists with mgr lock - take a reference
-	   for this list */
-	if (created) {
-		mutex_lock(&mgr->lock);
-		drm_dp_mst_topology_get_port(port);
-		list_add(&port->next, &mstb->ports);
-		mstb->num_ports++;
-		mutex_unlock(&mgr->lock);
-	}
-
-	/*
-	 * Reprobe PBN caps on both hotplug, and when re-probing the link
-	 * for our parent mstb
-	 */
-	if (old_ddps != port->ddps || !created) {
-		if (port->ddps && !port->input) {
-			ret = drm_dp_send_enum_path_resources(mgr, mstb,
-							      port);
-			if (ret == 1)
-				changed = true;
-		} else {
-			port->full_pbn = 0;
-		}
-	}
-
-	ret = drm_dp_port_set_pdt(port, new_pdt, new_mcs);
-	if (ret == 1) {
-		send_link_addr = true;
-	} else if (ret < 0) {
-		drm_err(dev, "Failed to change PDT on port %p: %d\n", port, ret);
-		goto fail;
-	}
-
-	/*
-	 * If this port wasn't just created, then we're reprobing because
-	 * we're coming out of suspend. In this case, always resend the link
-	 * address if there's an MSTB on this port
-	 */
-	if (!created && port->pdt == DP_PEER_DEVICE_MST_BRANCHING &&
-	    port->mcs)
-		send_link_addr = true;
-
-	if (port->connector)
-		drm_modeset_unlock(&mgr->base.lock);
-	else if (!port->input)
-		drm_dp_mst_port_add_connector(mstb, port);
-
-	if (send_link_addr && port->mstb) {
-		ret = drm_dp_send_link_address(mgr, port->mstb);
-		if (ret == 1) /* MSTB below us changed */
-			changed = true;
-		else if (ret < 0)
-			goto fail_put;
-	}
-
-	/* put reference to this port */
-	drm_dp_mst_topology_put_port(port);
-	return changed;
-
-fail:
-	drm_dp_mst_topology_unlink_port(mgr, port);
-	if (port->connector)
-		drm_modeset_unlock(&mgr->base.lock);
-fail_put:
-	drm_dp_mst_topology_put_port(port);
-	return ret;
-}
-
-static void
-drm_dp_mst_handle_conn_stat(struct drm_dp_mst_branch *mstb,
-			    struct drm_dp_connection_status_notify *conn_stat)
-{
-	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
-	struct drm_dp_mst_port *port;
-	int old_ddps, ret;
-	u8 new_pdt;
-	bool new_mcs;
-	bool dowork = false, create_connector = false;
-
-	port = drm_dp_get_port(mstb, conn_stat->port_number);
-	if (!port)
-		return;
-
-	if (port->connector) {
-		if (!port->input && conn_stat->input_port) {
-			/*
-			 * We can't remove a connector from an already exposed
-			 * port, so just throw the port out and make sure we
-			 * reprobe the link address of it's parent MSTB
-			 */
-			drm_dp_mst_topology_unlink_port(mgr, port);
-			mstb->link_address_sent = false;
-			dowork = true;
-			goto out;
-		}
-
-		/* Locking is only needed if the port's exposed to userspace */
-		drm_modeset_lock(&mgr->base.lock, NULL);
-	} else if (port->input && !conn_stat->input_port) {
-		create_connector = true;
-		/* Reprobe link address so we get num_sdp_streams */
-		mstb->link_address_sent = false;
-		dowork = true;
-	}
-
-	old_ddps = port->ddps;
-	port->input = conn_stat->input_port;
-	port->ldps = conn_stat->legacy_device_plug_status;
-	port->ddps = conn_stat->displayport_device_plug_status;
-
-	if (old_ddps != port->ddps) {
-		if (port->ddps && !port->input)
-			drm_dp_send_enum_path_resources(mgr, mstb, port);
-		else
-			port->full_pbn = 0;
-	}
-
-	new_pdt = port->input ? DP_PEER_DEVICE_NONE : conn_stat->peer_device_type;
-	new_mcs = conn_stat->message_capability_status;
-	ret = drm_dp_port_set_pdt(port, new_pdt, new_mcs);
-	if (ret == 1) {
-		dowork = true;
-	} else if (ret < 0) {
-		drm_err(mgr->dev, "Failed to change PDT for port %p: %d\n", port, ret);
-		dowork = false;
-	}
-
-	if (port->connector)
-		drm_modeset_unlock(&mgr->base.lock);
-	else if (create_connector)
-		drm_dp_mst_port_add_connector(mstb, port);
-
-out:
-	drm_dp_mst_topology_put_port(port);
-	if (dowork)
-		queue_work(system_long_wq, &mstb->mgr->work);
-}
-
-static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_topology_mgr *mgr,
-							       u8 lct, u8 *rad)
-{
-	struct drm_dp_mst_branch *mstb;
-	struct drm_dp_mst_port *port;
-	int i, ret;
-	/* find the port by iterating down */
-
-	mutex_lock(&mgr->lock);
-	mstb = mgr->mst_primary;
-
-	if (!mstb)
-		goto out;
-
-	for (i = 0; i < lct - 1; i++) {
-		int shift = (i % 2) ? 0 : 4;
-		int port_num = (rad[i / 2] >> shift) & 0xf;
-
-		list_for_each_entry(port, &mstb->ports, next) {
-			if (port->port_num == port_num) {
-				mstb = port->mstb;
-				if (!mstb) {
-					drm_err(mgr->dev,
-						"failed to lookup MSTB with lct %d, rad %02x\n",
-						lct, rad[0]);
-					goto out;
-				}
-
-				break;
-			}
-		}
-	}
-	ret = drm_dp_mst_topology_try_get_mstb(mstb);
-	if (!ret)
-		mstb = NULL;
-out:
-	mutex_unlock(&mgr->lock);
-	return mstb;
-}
-
-static struct drm_dp_mst_branch *get_mst_branch_device_by_guid_helper(
-	struct drm_dp_mst_branch *mstb,
-	const uint8_t *guid)
-{
-	struct drm_dp_mst_branch *found_mstb;
-	struct drm_dp_mst_port *port;
-
-	if (memcmp(mstb->guid, guid, 16) == 0)
-		return mstb;
-
-
-	list_for_each_entry(port, &mstb->ports, next) {
-		if (!port->mstb)
-			continue;
-
-		found_mstb = get_mst_branch_device_by_guid_helper(port->mstb, guid);
-
-		if (found_mstb)
-			return found_mstb;
-	}
-
-	return NULL;
-}
-
-static struct drm_dp_mst_branch *
-drm_dp_get_mst_branch_device_by_guid(struct drm_dp_mst_topology_mgr *mgr,
-				     const uint8_t *guid)
-{
-	struct drm_dp_mst_branch *mstb;
-	int ret;
-
-	/* find the port by iterating down */
-	mutex_lock(&mgr->lock);
-
-	mstb = get_mst_branch_device_by_guid_helper(mgr->mst_primary, guid);
-	if (mstb) {
-		ret = drm_dp_mst_topology_try_get_mstb(mstb);
-		if (!ret)
-			mstb = NULL;
-	}
-
-	mutex_unlock(&mgr->lock);
-	return mstb;
-}
-
-static int drm_dp_check_and_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
-					       struct drm_dp_mst_branch *mstb)
-{
-	struct drm_dp_mst_port *port;
-	int ret;
-	bool changed = false;
-
-	if (!mstb->link_address_sent) {
-		ret = drm_dp_send_link_address(mgr, mstb);
-		if (ret == 1)
-			changed = true;
-		else if (ret < 0)
-			return ret;
-	}
-
-	list_for_each_entry(port, &mstb->ports, next) {
-		struct drm_dp_mst_branch *mstb_child = NULL;
-
-		if (port->input || !port->ddps)
-			continue;
-
-		if (port->mstb)
-			mstb_child = drm_dp_mst_topology_get_mstb_validated(
-			    mgr, port->mstb);
-
-		if (mstb_child) {
-			ret = drm_dp_check_and_send_link_address(mgr,
-								 mstb_child);
-			drm_dp_mst_topology_put_mstb(mstb_child);
-			if (ret == 1)
-				changed = true;
-			else if (ret < 0)
-				return ret;
-		}
-	}
-
-	return changed;
-}
-
-static void drm_dp_mst_link_probe_work(struct work_struct *work)
-{
-	struct drm_dp_mst_topology_mgr *mgr =
-		container_of(work, struct drm_dp_mst_topology_mgr, work);
-	struct drm_device *dev = mgr->dev;
-	struct drm_dp_mst_branch *mstb;
-	int ret;
-	bool clear_payload_id_table;
-
-	mutex_lock(&mgr->probe_lock);
-
-	mutex_lock(&mgr->lock);
-	clear_payload_id_table = !mgr->payload_id_table_cleared;
-	mgr->payload_id_table_cleared = true;
-
-	mstb = mgr->mst_primary;
-	if (mstb) {
-		ret = drm_dp_mst_topology_try_get_mstb(mstb);
-		if (!ret)
-			mstb = NULL;
-	}
-	mutex_unlock(&mgr->lock);
-	if (!mstb) {
-		mutex_unlock(&mgr->probe_lock);
-		return;
-	}
-
-	/*
-	 * Certain branch devices seem to incorrectly report an available_pbn
-	 * of 0 on downstream sinks, even after clearing the
-	 * DP_PAYLOAD_ALLOCATE_* registers in
-	 * drm_dp_mst_topology_mgr_set_mst(). Namely, the CableMatters USB-C
-	 * 2x DP hub. Sending a CLEAR_PAYLOAD_ID_TABLE message seems to make
-	 * things work again.
-	 */
-	if (clear_payload_id_table) {
-		drm_dbg_kms(dev, "Clearing payload ID table\n");
-		drm_dp_send_clear_payload_id_table(mgr, mstb);
-	}
-
-	ret = drm_dp_check_and_send_link_address(mgr, mstb);
-	drm_dp_mst_topology_put_mstb(mstb);
-
-	mutex_unlock(&mgr->probe_lock);
-	if (ret > 0)
-		drm_kms_helper_hotplug_event(dev);
-}
-
-static bool drm_dp_validate_guid(struct drm_dp_mst_topology_mgr *mgr,
-				 u8 *guid)
-{
-	u64 salt;
-
-	if (memchr_inv(guid, 0, 16))
-		return true;
-
-	salt = get_jiffies_64();
-
-	memcpy(&guid[0], &salt, sizeof(u64));
-	memcpy(&guid[8], &salt, sizeof(u64));
-
-	return false;
-}
-
-static void build_dpcd_read(struct drm_dp_sideband_msg_tx *msg,
-			    u8 port_num, u32 offset, u8 num_bytes)
-{
-	struct drm_dp_sideband_msg_req_body req;
-
-	req.req_type = DP_REMOTE_DPCD_READ;
-	req.u.dpcd_read.port_number = port_num;
-	req.u.dpcd_read.dpcd_address = offset;
-	req.u.dpcd_read.num_bytes = num_bytes;
-	drm_dp_encode_sideband_req(&req, msg);
-}
-
-static int drm_dp_send_sideband_msg(struct drm_dp_mst_topology_mgr *mgr,
-				    bool up, u8 *msg, int len)
-{
-	int ret;
-	int regbase = up ? DP_SIDEBAND_MSG_UP_REP_BASE : DP_SIDEBAND_MSG_DOWN_REQ_BASE;
-	int tosend, total, offset;
-	int retries = 0;
-
-retry:
-	total = len;
-	offset = 0;
-	do {
-		tosend = min3(mgr->max_dpcd_transaction_bytes, 16, total);
-
-		ret = drm_dp_dpcd_write(mgr->aux, regbase + offset,
-					&msg[offset],
-					tosend);
-		if (ret != tosend) {
-			if (ret == -EIO && retries < 5) {
-				retries++;
-				goto retry;
-			}
-			drm_dbg_kms(mgr->dev, "failed to dpcd write %d %d\n", tosend, ret);
-
-			return -EIO;
-		}
-		offset += tosend;
-		total -= tosend;
-	} while (total > 0);
-	return 0;
-}
-
-static int set_hdr_from_dst_qlock(struct drm_dp_sideband_msg_hdr *hdr,
-				  struct drm_dp_sideband_msg_tx *txmsg)
-{
-	struct drm_dp_mst_branch *mstb = txmsg->dst;
-	u8 req_type;
-
-	req_type = txmsg->msg[0] & 0x7f;
-	if (req_type == DP_CONNECTION_STATUS_NOTIFY ||
-		req_type == DP_RESOURCE_STATUS_NOTIFY ||
-		req_type == DP_CLEAR_PAYLOAD_ID_TABLE)
-		hdr->broadcast = 1;
-	else
-		hdr->broadcast = 0;
-	hdr->path_msg = txmsg->path_msg;
-	if (hdr->broadcast) {
-		hdr->lct = 1;
-		hdr->lcr = 6;
-	} else {
-		hdr->lct = mstb->lct;
-		hdr->lcr = mstb->lct - 1;
-	}
-
-	memcpy(hdr->rad, mstb->rad, hdr->lct / 2);
-
-	return 0;
-}
-/*
- * process a single block of the next message in the sideband queue
- */
-static int process_single_tx_qlock(struct drm_dp_mst_topology_mgr *mgr,
-				   struct drm_dp_sideband_msg_tx *txmsg,
-				   bool up)
-{
-	u8 chunk[48];
-	struct drm_dp_sideband_msg_hdr hdr;
-	int len, space, idx, tosend;
-	int ret;
-
-	if (txmsg->state == DRM_DP_SIDEBAND_TX_SENT)
-		return 0;
-
-	memset(&hdr, 0, sizeof(struct drm_dp_sideband_msg_hdr));
-
-	if (txmsg->state == DRM_DP_SIDEBAND_TX_QUEUED)
-		txmsg->state = DRM_DP_SIDEBAND_TX_START_SEND;
-
-	/* make hdr from dst mst */
-	ret = set_hdr_from_dst_qlock(&hdr, txmsg);
-	if (ret < 0)
-		return ret;
-
-	/* amount left to send in this message */
-	len = txmsg->cur_len - txmsg->cur_offset;
-
-	/* 48 - sideband msg size - 1 byte for data CRC, x header bytes */
-	space = 48 - 1 - drm_dp_calc_sb_hdr_size(&hdr);
-
-	tosend = min(len, space);
-	if (len == txmsg->cur_len)
-		hdr.somt = 1;
-	if (space >= len)
-		hdr.eomt = 1;
-
-
-	hdr.msg_len = tosend + 1;
-	drm_dp_encode_sideband_msg_hdr(&hdr, chunk, &idx);
-	memcpy(&chunk[idx], &txmsg->msg[txmsg->cur_offset], tosend);
-	/* add crc at end */
-	drm_dp_crc_sideband_chunk_req(&chunk[idx], tosend);
-	idx += tosend + 1;
-
-	ret = drm_dp_send_sideband_msg(mgr, up, chunk, idx);
-	if (ret) {
-		if (drm_debug_enabled(DRM_UT_DP)) {
-			struct drm_printer p = drm_debug_printer(DBG_PREFIX);
-
-			drm_printf(&p, "sideband msg failed to send\n");
-			drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
-		}
-		return ret;
-	}
-
-	txmsg->cur_offset += tosend;
-	if (txmsg->cur_offset == txmsg->cur_len) {
-		txmsg->state = DRM_DP_SIDEBAND_TX_SENT;
-		return 1;
-	}
-	return 0;
-}
-
-static void process_single_down_tx_qlock(struct drm_dp_mst_topology_mgr *mgr)
-{
-	struct drm_dp_sideband_msg_tx *txmsg;
-	int ret;
-
-	WARN_ON(!mutex_is_locked(&mgr->qlock));
-
-	/* construct a chunk from the first msg in the tx_msg queue */
-	if (list_empty(&mgr->tx_msg_downq))
-		return;
-
-	txmsg = list_first_entry(&mgr->tx_msg_downq,
-				 struct drm_dp_sideband_msg_tx, next);
-	ret = process_single_tx_qlock(mgr, txmsg, false);
-	if (ret < 0) {
-		drm_dbg_kms(mgr->dev, "failed to send msg in q %d\n", ret);
-		list_del(&txmsg->next);
-		txmsg->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
-		wake_up_all(&mgr->tx_waitq);
-	}
-}
-
-static void drm_dp_queue_down_tx(struct drm_dp_mst_topology_mgr *mgr,
-				 struct drm_dp_sideband_msg_tx *txmsg)
-{
-	mutex_lock(&mgr->qlock);
-	list_add_tail(&txmsg->next, &mgr->tx_msg_downq);
-
-	if (drm_debug_enabled(DRM_UT_DP)) {
-		struct drm_printer p = drm_debug_printer(DBG_PREFIX);
-
-		drm_dp_mst_dump_sideband_msg_tx(&p, txmsg);
-	}
-
-	if (list_is_singular(&mgr->tx_msg_downq))
-		process_single_down_tx_qlock(mgr);
-	mutex_unlock(&mgr->qlock);
-}
-
-static void
-drm_dp_dump_link_address(const struct drm_dp_mst_topology_mgr *mgr,
-			 struct drm_dp_link_address_ack_reply *reply)
-{
-	struct drm_dp_link_addr_reply_port *port_reply;
-	int i;
-
-	for (i = 0; i < reply->nports; i++) {
-		port_reply = &reply->ports[i];
-		drm_dbg_kms(mgr->dev,
-			    "port %d: input %d, pdt: %d, pn: %d, dpcd_rev: %02x, mcs: %d, ddps: %d, ldps %d, sdp %d/%d\n",
-			    i,
-			    port_reply->input_port,
-			    port_reply->peer_device_type,
-			    port_reply->port_number,
-			    port_reply->dpcd_revision,
-			    port_reply->mcs,
-			    port_reply->ddps,
-			    port_reply->legacy_device_plug_status,
-			    port_reply->num_sdp_streams,
-			    port_reply->num_sdp_stream_sinks);
-	}
-}
-
-static int drm_dp_send_link_address(struct drm_dp_mst_topology_mgr *mgr,
-				     struct drm_dp_mst_branch *mstb)
-{
-	struct drm_dp_sideband_msg_tx *txmsg;
-	struct drm_dp_link_address_ack_reply *reply;
-	struct drm_dp_mst_port *port, *tmp;
-	int i, ret, port_mask = 0;
-	bool changed = false;
-
-	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
-	if (!txmsg)
-		return -ENOMEM;
-
-	txmsg->dst = mstb;
-	build_link_address(txmsg);
-
-	mstb->link_address_sent = true;
-	drm_dp_queue_down_tx(mgr, txmsg);
-
-	/* FIXME: Actually do some real error handling here */
-	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
-	if (ret <= 0) {
-		drm_err(mgr->dev, "Sending link address failed with %d\n", ret);
-		goto out;
-	}
-	if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
-		drm_err(mgr->dev, "link address NAK received\n");
-		ret = -EIO;
-		goto out;
-	}
-
-	reply = &txmsg->reply.u.link_addr;
-	drm_dbg_kms(mgr->dev, "link address reply: %d\n", reply->nports);
-	drm_dp_dump_link_address(mgr, reply);
-
-	ret = drm_dp_check_mstb_guid(mstb, reply->guid);
-	if (ret) {
-		char buf[64];
-
-		drm_dp_mst_rad_to_str(mstb->rad, mstb->lct, buf, sizeof(buf));
-		drm_err(mgr->dev, "GUID check on %s failed: %d\n", buf, ret);
-		goto out;
-	}
-
-	for (i = 0; i < reply->nports; i++) {
-		port_mask |= BIT(reply->ports[i].port_number);
-		ret = drm_dp_mst_handle_link_address_port(mstb, mgr->dev,
-							  &reply->ports[i]);
-		if (ret == 1)
-			changed = true;
-		else if (ret < 0)
-			goto out;
-	}
-
-	/* Prune any ports that are currently a part of mstb in our in-memory
-	 * topology, but were not seen in this link address. Usually this
-	 * means that they were removed while the topology was out of sync,
-	 * e.g. during suspend/resume
-	 */
-	mutex_lock(&mgr->lock);
-	list_for_each_entry_safe(port, tmp, &mstb->ports, next) {
-		if (port_mask & BIT(port->port_num))
-			continue;
-
-		drm_dbg_kms(mgr->dev, "port %d was not in link address, removing\n",
-			    port->port_num);
-		list_del(&port->next);
-		drm_dp_mst_topology_put_port(port);
-		changed = true;
-	}
-	mutex_unlock(&mgr->lock);
-
-out:
-	if (ret <= 0)
-		mstb->link_address_sent = false;
-	kfree(txmsg);
-	return ret < 0 ? ret : changed;
-}
-
-static void
-drm_dp_send_clear_payload_id_table(struct drm_dp_mst_topology_mgr *mgr,
-				   struct drm_dp_mst_branch *mstb)
-{
-	struct drm_dp_sideband_msg_tx *txmsg;
-	int ret;
-
-	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
-	if (!txmsg)
-		return;
-
-	txmsg->dst = mstb;
-	build_clear_payload_id_table(txmsg);
-
-	drm_dp_queue_down_tx(mgr, txmsg);
-
-	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
-	if (ret > 0 && txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
-		drm_dbg_kms(mgr->dev, "clear payload table id nak received\n");
-
-	kfree(txmsg);
-}
-
-static int
-drm_dp_send_enum_path_resources(struct drm_dp_mst_topology_mgr *mgr,
-				struct drm_dp_mst_branch *mstb,
-				struct drm_dp_mst_port *port)
-{
-	struct drm_dp_enum_path_resources_ack_reply *path_res;
-	struct drm_dp_sideband_msg_tx *txmsg;
-	int ret;
-
-	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
-	if (!txmsg)
-		return -ENOMEM;
-
-	txmsg->dst = mstb;
-	build_enum_path_resources(txmsg, port->port_num);
-
-	drm_dp_queue_down_tx(mgr, txmsg);
-
-	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
-	if (ret > 0) {
-		ret = 0;
-		path_res = &txmsg->reply.u.path_resources;
-
-		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
-			drm_dbg_kms(mgr->dev, "enum path resources nak received\n");
-		} else {
-			if (port->port_num != path_res->port_number)
-				DRM_ERROR("got incorrect port in response\n");
-
-			drm_dbg_kms(mgr->dev, "enum path resources %d: %d %d\n",
-				    path_res->port_number,
-				    path_res->full_payload_bw_number,
-				    path_res->avail_payload_bw_number);
-
-			/*
-			 * If something changed, make sure we send a
-			 * hotplug
-			 */
-			if (port->full_pbn != path_res->full_payload_bw_number ||
-			    port->fec_capable != path_res->fec_capable)
-				ret = 1;
-
-			port->full_pbn = path_res->full_payload_bw_number;
-			port->fec_capable = path_res->fec_capable;
-		}
-	}
-
-	kfree(txmsg);
-	return ret;
-}
-
-static struct drm_dp_mst_port *drm_dp_get_last_connected_port_to_mstb(struct drm_dp_mst_branch *mstb)
-{
-	if (!mstb->port_parent)
-		return NULL;
-
-	if (mstb->port_parent->mstb != mstb)
-		return mstb->port_parent;
-
-	return drm_dp_get_last_connected_port_to_mstb(mstb->port_parent->parent);
-}
-
-/*
- * Searches upwards in the topology starting from mstb to try to find the
- * closest available parent of mstb that's still connected to the rest of the
- * topology. This can be used in order to perform operations like releasing
- * payloads, where the branch device which owned the payload may no longer be
- * around and thus would require that the payload on the last living relative
- * be freed instead.
- */
-static struct drm_dp_mst_branch *
-drm_dp_get_last_connected_port_and_mstb(struct drm_dp_mst_topology_mgr *mgr,
-					struct drm_dp_mst_branch *mstb,
-					int *port_num)
-{
-	struct drm_dp_mst_branch *rmstb = NULL;
-	struct drm_dp_mst_port *found_port;
-
-	mutex_lock(&mgr->lock);
-	if (!mgr->mst_primary)
-		goto out;
-
-	do {
-		found_port = drm_dp_get_last_connected_port_to_mstb(mstb);
-		if (!found_port)
-			break;
-
-		if (drm_dp_mst_topology_try_get_mstb(found_port->parent)) {
-			rmstb = found_port->parent;
-			*port_num = found_port->port_num;
-		} else {
-			/* Search again, starting from this parent */
-			mstb = found_port->parent;
-		}
-	} while (!rmstb);
-out:
-	mutex_unlock(&mgr->lock);
-	return rmstb;
-}
-
-static int drm_dp_payload_send_msg(struct drm_dp_mst_topology_mgr *mgr,
-				   struct drm_dp_mst_port *port,
-				   int id,
-				   int pbn)
-{
-	struct drm_dp_sideband_msg_tx *txmsg;
-	struct drm_dp_mst_branch *mstb;
-	int ret, port_num;
-	u8 sinks[DRM_DP_MAX_SDP_STREAMS];
-	int i;
-
-	port_num = port->port_num;
-	mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
-	if (!mstb) {
-		mstb = drm_dp_get_last_connected_port_and_mstb(mgr,
-							       port->parent,
-							       &port_num);
-
-		if (!mstb)
-			return -EINVAL;
-	}
-
-	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
-	if (!txmsg) {
-		ret = -ENOMEM;
-		goto fail_put;
-	}
-
-	for (i = 0; i < port->num_sdp_streams; i++)
-		sinks[i] = i;
-
-	txmsg->dst = mstb;
-	build_allocate_payload(txmsg, port_num,
-			       id,
-			       pbn, port->num_sdp_streams, sinks);
-
-	drm_dp_queue_down_tx(mgr, txmsg);
-
-	/*
-	 * FIXME: there is a small chance that between getting the last
-	 * connected mstb and sending the payload message, the last connected
-	 * mstb could also be removed from the topology. In the future, this
-	 * needs to be fixed by restarting the
-	 * drm_dp_get_last_connected_port_and_mstb() search in the event of a
-	 * timeout if the topology is still connected to the system.
-	 */
-	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
-	if (ret > 0) {
-		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
-			ret = -EINVAL;
-		else
-			ret = 0;
-	}
-	kfree(txmsg);
-fail_put:
-	drm_dp_mst_topology_put_mstb(mstb);
-	return ret;
-}
-
-int drm_dp_send_power_updown_phy(struct drm_dp_mst_topology_mgr *mgr,
-				 struct drm_dp_mst_port *port, bool power_up)
-{
-	struct drm_dp_sideband_msg_tx *txmsg;
-	int ret;
-
-	port = drm_dp_mst_topology_get_port_validated(mgr, port);
-	if (!port)
-		return -EINVAL;
-
-	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
-	if (!txmsg) {
-		drm_dp_mst_topology_put_port(port);
-		return -ENOMEM;
-	}
-
-	txmsg->dst = port->parent;
-	build_power_updown_phy(txmsg, port->port_num, power_up);
-	drm_dp_queue_down_tx(mgr, txmsg);
-
-	ret = drm_dp_mst_wait_tx_reply(port->parent, txmsg);
-	if (ret > 0) {
-		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
-			ret = -EINVAL;
-		else
-			ret = 0;
-	}
-	kfree(txmsg);
-	drm_dp_mst_topology_put_port(port);
-
-	return ret;
-}
-EXPORT_SYMBOL(drm_dp_send_power_updown_phy);
-
-int drm_dp_send_query_stream_enc_status(struct drm_dp_mst_topology_mgr *mgr,
-		struct drm_dp_mst_port *port,
-		struct drm_dp_query_stream_enc_status_ack_reply *status)
-{
-	struct drm_dp_sideband_msg_tx *txmsg;
-	u8 nonce[7];
-	int ret;
-
-	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
-	if (!txmsg)
-		return -ENOMEM;
-
-	port = drm_dp_mst_topology_get_port_validated(mgr, port);
-	if (!port) {
-		ret = -EINVAL;
-		goto out_get_port;
-	}
-
-	get_random_bytes(nonce, sizeof(nonce));
-
-	/*
-	 * "Source device targets the QUERY_STREAM_ENCRYPTION_STATUS message
-	 *  transaction at the MST Branch device directly connected to the
-	 *  Source"
-	 */
-	txmsg->dst = mgr->mst_primary;
-
-	build_query_stream_enc_status(txmsg, port->vcpi.vcpi, nonce);
-
-	drm_dp_queue_down_tx(mgr, txmsg);
-
-	ret = drm_dp_mst_wait_tx_reply(mgr->mst_primary, txmsg);
-	if (ret < 0) {
-		goto out;
-	} else if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
-		drm_dbg_kms(mgr->dev, "query encryption status nak received\n");
-		ret = -ENXIO;
-		goto out;
-	}
-
-	ret = 0;
-	memcpy(status, &txmsg->reply.u.enc_status, sizeof(*status));
-
-out:
-	drm_dp_mst_topology_put_port(port);
-out_get_port:
-	kfree(txmsg);
-	return ret;
-}
-EXPORT_SYMBOL(drm_dp_send_query_stream_enc_status);
-
-static int drm_dp_create_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
-				       int id,
-				       struct drm_dp_payload *payload)
-{
-	int ret;
-
-	ret = drm_dp_dpcd_write_payload(mgr, id, payload);
-	if (ret < 0) {
-		payload->payload_state = 0;
-		return ret;
-	}
-	payload->payload_state = DP_PAYLOAD_LOCAL;
-	return 0;
-}
-
-static int drm_dp_create_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
-				       struct drm_dp_mst_port *port,
-				       int id,
-				       struct drm_dp_payload *payload)
-{
-	int ret;
-
-	ret = drm_dp_payload_send_msg(mgr, port, id, port->vcpi.pbn);
-	if (ret < 0)
-		return ret;
-	payload->payload_state = DP_PAYLOAD_REMOTE;
-	return ret;
-}
-
-static int drm_dp_destroy_payload_step1(struct drm_dp_mst_topology_mgr *mgr,
-					struct drm_dp_mst_port *port,
-					int id,
-					struct drm_dp_payload *payload)
-{
-	drm_dbg_kms(mgr->dev, "\n");
-	/* it's okay for these to fail */
-	if (port) {
-		drm_dp_payload_send_msg(mgr, port, id, 0);
-	}
-
-	drm_dp_dpcd_write_payload(mgr, id, payload);
-	payload->payload_state = DP_PAYLOAD_DELETE_LOCAL;
-	return 0;
-}
-
-static int drm_dp_destroy_payload_step2(struct drm_dp_mst_topology_mgr *mgr,
-					int id,
-					struct drm_dp_payload *payload)
-{
-	payload->payload_state = 0;
-	return 0;
-}
-
-/**
- * drm_dp_update_payload_part1() - Execute payload update part 1
- * @mgr: manager to use.
- * @start_slot: this is the cur slot
- *
- * NOTE: start_slot is a temporary workaround for non-atomic drivers,
- * this will be removed when non-atomic mst helpers are moved out of the helper
- *
- * This iterates over all proposed virtual channels, and tries to
- * allocate space in the link for them. For 0->slots transitions,
- * this step just writes the VCPI to the MST device. For slots->0
- * transitions, this writes the updated VCPIs and removes the
- * remote VC payloads.
- *
- * after calling this the driver should generate ACT and payload
- * packets.
- */
-int drm_dp_update_payload_part1(struct drm_dp_mst_topology_mgr *mgr, int start_slot)
-{
-	struct drm_dp_payload req_payload;
-	struct drm_dp_mst_port *port;
-	int i, j;
-	int cur_slots = start_slot;
-	bool skip;
-
-	mutex_lock(&mgr->payload_lock);
-	for (i = 0; i < mgr->max_payloads; i++) {
-		struct drm_dp_vcpi *vcpi = mgr->proposed_vcpis[i];
-		struct drm_dp_payload *payload = &mgr->payloads[i];
-		bool put_port = false;
-
-		/* solve the current payloads - compare to the hw ones
-		   - update the hw view */
-		req_payload.start_slot = cur_slots;
-		if (vcpi) {
-			port = container_of(vcpi, struct drm_dp_mst_port,
-					    vcpi);
-
-			mutex_lock(&mgr->lock);
-			skip = !drm_dp_mst_port_downstream_of_branch(port, mgr->mst_primary);
-			mutex_unlock(&mgr->lock);
-
-			if (skip) {
-				drm_dbg_kms(mgr->dev,
-					    "Virtual channel %d is not in current topology\n",
-					    i);
-				continue;
-			}
-			/* Validated ports don't matter if we're releasing
-			 * VCPI
-			 */
-			if (vcpi->num_slots) {
-				port = drm_dp_mst_topology_get_port_validated(
-				    mgr, port);
-				if (!port) {
-					if (vcpi->num_slots == payload->num_slots) {
-						cur_slots += vcpi->num_slots;
-						payload->start_slot = req_payload.start_slot;
-						continue;
-					} else {
-						drm_dbg_kms(mgr->dev,
-							    "Fail:set payload to invalid sink");
-						mutex_unlock(&mgr->payload_lock);
-						return -EINVAL;
-					}
-				}
-				put_port = true;
-			}
-
-			req_payload.num_slots = vcpi->num_slots;
-			req_payload.vcpi = vcpi->vcpi;
-		} else {
-			port = NULL;
-			req_payload.num_slots = 0;
-		}
-
-		payload->start_slot = req_payload.start_slot;
-		/* work out what is required to happen with this payload */
-		if (payload->num_slots != req_payload.num_slots) {
-
-			/* need to push an update for this payload */
-			if (req_payload.num_slots) {
-				drm_dp_create_payload_step1(mgr, vcpi->vcpi,
-							    &req_payload);
-				payload->num_slots = req_payload.num_slots;
-				payload->vcpi = req_payload.vcpi;
-
-			} else if (payload->num_slots) {
-				payload->num_slots = 0;
-				drm_dp_destroy_payload_step1(mgr, port,
-							     payload->vcpi,
-							     payload);
-				req_payload.payload_state =
-					payload->payload_state;
-				payload->start_slot = 0;
-			}
-			payload->payload_state = req_payload.payload_state;
-		}
-		cur_slots += req_payload.num_slots;
-
-		if (put_port)
-			drm_dp_mst_topology_put_port(port);
-	}
-
-	for (i = 0; i < mgr->max_payloads; /* do nothing */) {
-		if (mgr->payloads[i].payload_state != DP_PAYLOAD_DELETE_LOCAL) {
-			i++;
-			continue;
-		}
-
-		drm_dbg_kms(mgr->dev, "removing payload %d\n", i);
-		for (j = i; j < mgr->max_payloads - 1; j++) {
-			mgr->payloads[j] = mgr->payloads[j + 1];
-			mgr->proposed_vcpis[j] = mgr->proposed_vcpis[j + 1];
-
-			if (mgr->proposed_vcpis[j] &&
-			    mgr->proposed_vcpis[j]->num_slots) {
-				set_bit(j + 1, &mgr->payload_mask);
-			} else {
-				clear_bit(j + 1, &mgr->payload_mask);
-			}
-		}
-
-		memset(&mgr->payloads[mgr->max_payloads - 1], 0,
-		       sizeof(struct drm_dp_payload));
-		mgr->proposed_vcpis[mgr->max_payloads - 1] = NULL;
-		clear_bit(mgr->max_payloads, &mgr->payload_mask);
-	}
-	mutex_unlock(&mgr->payload_lock);
-
-	return 0;
-}
-EXPORT_SYMBOL(drm_dp_update_payload_part1);
-
-/**
- * drm_dp_update_payload_part2() - Execute payload update part 2
- * @mgr: manager to use.
- *
- * This iterates over all proposed virtual channels, and tries to
- * allocate space in the link for them. For 0->slots transitions,
- * this step writes the remote VC payload commands. For slots->0
- * this just resets some internal state.
- */
-int drm_dp_update_payload_part2(struct drm_dp_mst_topology_mgr *mgr)
-{
-	struct drm_dp_mst_port *port;
-	int i;
-	int ret = 0;
-	bool skip;
-
-	mutex_lock(&mgr->payload_lock);
-	for (i = 0; i < mgr->max_payloads; i++) {
-
-		if (!mgr->proposed_vcpis[i])
-			continue;
-
-		port = container_of(mgr->proposed_vcpis[i], struct drm_dp_mst_port, vcpi);
-
-		mutex_lock(&mgr->lock);
-		skip = !drm_dp_mst_port_downstream_of_branch(port, mgr->mst_primary);
-		mutex_unlock(&mgr->lock);
-
-		if (skip)
-			continue;
-
-		drm_dbg_kms(mgr->dev, "payload %d %d\n", i, mgr->payloads[i].payload_state);
-		if (mgr->payloads[i].payload_state == DP_PAYLOAD_LOCAL) {
-			ret = drm_dp_create_payload_step2(mgr, port, mgr->proposed_vcpis[i]->vcpi, &mgr->payloads[i]);
-		} else if (mgr->payloads[i].payload_state == DP_PAYLOAD_DELETE_LOCAL) {
-			ret = drm_dp_destroy_payload_step2(mgr, mgr->proposed_vcpis[i]->vcpi, &mgr->payloads[i]);
-		}
-		if (ret) {
-			mutex_unlock(&mgr->payload_lock);
-			return ret;
-		}
-	}
-	mutex_unlock(&mgr->payload_lock);
-	return 0;
-}
-EXPORT_SYMBOL(drm_dp_update_payload_part2);
-
-static int drm_dp_send_dpcd_read(struct drm_dp_mst_topology_mgr *mgr,
-				 struct drm_dp_mst_port *port,
-				 int offset, int size, u8 *bytes)
-{
-	int ret = 0;
-	struct drm_dp_sideband_msg_tx *txmsg;
-	struct drm_dp_mst_branch *mstb;
-
-	mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
-	if (!mstb)
-		return -EINVAL;
-
-	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
-	if (!txmsg) {
-		ret = -ENOMEM;
-		goto fail_put;
-	}
-
-	build_dpcd_read(txmsg, port->port_num, offset, size);
-	txmsg->dst = port->parent;
-
-	drm_dp_queue_down_tx(mgr, txmsg);
-
-	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
-	if (ret < 0)
-		goto fail_free;
-
-	/* DPCD read should never be NACKed */
-	if (txmsg->reply.reply_type == 1) {
-		drm_err(mgr->dev, "mstb %p port %d: DPCD read on addr 0x%x for %d bytes NAKed\n",
-			mstb, port->port_num, offset, size);
-		ret = -EIO;
-		goto fail_free;
-	}
-
-	if (txmsg->reply.u.remote_dpcd_read_ack.num_bytes != size) {
-		ret = -EPROTO;
-		goto fail_free;
-	}
-
-	ret = min_t(size_t, txmsg->reply.u.remote_dpcd_read_ack.num_bytes,
-		    size);
-	memcpy(bytes, txmsg->reply.u.remote_dpcd_read_ack.bytes, ret);
-
-fail_free:
-	kfree(txmsg);
-fail_put:
-	drm_dp_mst_topology_put_mstb(mstb);
-
-	return ret;
-}
-
-static int drm_dp_send_dpcd_write(struct drm_dp_mst_topology_mgr *mgr,
-				  struct drm_dp_mst_port *port,
-				  int offset, int size, u8 *bytes)
-{
-	int ret;
-	struct drm_dp_sideband_msg_tx *txmsg;
-	struct drm_dp_mst_branch *mstb;
-
-	mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
-	if (!mstb)
-		return -EINVAL;
-
-	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
-	if (!txmsg) {
-		ret = -ENOMEM;
-		goto fail_put;
-	}
-
-	build_dpcd_write(txmsg, port->port_num, offset, size, bytes);
-	txmsg->dst = mstb;
-
-	drm_dp_queue_down_tx(mgr, txmsg);
-
-	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
-	if (ret > 0) {
-		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK)
-			ret = -EIO;
-		else
-			ret = size;
-	}
-
-	kfree(txmsg);
-fail_put:
-	drm_dp_mst_topology_put_mstb(mstb);
-	return ret;
-}
-
-static int drm_dp_encode_up_ack_reply(struct drm_dp_sideband_msg_tx *msg, u8 req_type)
-{
-	struct drm_dp_sideband_msg_reply_body reply;
-
-	reply.reply_type = DP_SIDEBAND_REPLY_ACK;
-	reply.req_type = req_type;
-	drm_dp_encode_sideband_reply(&reply, msg);
-	return 0;
-}
-
-static int drm_dp_send_up_ack_reply(struct drm_dp_mst_topology_mgr *mgr,
-				    struct drm_dp_mst_branch *mstb,
-				    int req_type, bool broadcast)
-{
-	struct drm_dp_sideband_msg_tx *txmsg;
-
-	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
-	if (!txmsg)
-		return -ENOMEM;
-
-	txmsg->dst = mstb;
-	drm_dp_encode_up_ack_reply(txmsg, req_type);
-
-	mutex_lock(&mgr->qlock);
-	/* construct a chunk from the first msg in the tx_msg queue */
-	process_single_tx_qlock(mgr, txmsg, true);
-	mutex_unlock(&mgr->qlock);
-
-	kfree(txmsg);
-	return 0;
-}
-
-/**
- * drm_dp_get_vc_payload_bw - get the VC payload BW for an MST link
- * @mgr: The &drm_dp_mst_topology_mgr to use
- * @link_rate: link rate in 10kbits/s units
- * @link_lane_count: lane count
- *
- * Calculate the total bandwidth of a MultiStream Transport link. The returned
- * value is in units of PBNs/(timeslots/1 MTP). This value can be used to
- * convert the number of PBNs required for a given stream to the number of
- * timeslots this stream requires in each MTP.
- */
-int drm_dp_get_vc_payload_bw(const struct drm_dp_mst_topology_mgr *mgr,
-			     int link_rate, int link_lane_count)
-{
-	if (link_rate == 0 || link_lane_count == 0)
-		drm_dbg_kms(mgr->dev, "invalid link rate/lane count: (%d / %d)\n",
-			    link_rate, link_lane_count);
-
-	/* See DP v2.0 2.6.4.2, VCPayload_Bandwidth_for_OneTimeSlotPer_MTP_Allocation */
-	return link_rate * link_lane_count / 54000;
-}
-EXPORT_SYMBOL(drm_dp_get_vc_payload_bw);
-
-/**
- * drm_dp_read_mst_cap() - check whether or not a sink supports MST
- * @aux: The DP AUX channel to use
- * @dpcd: A cached copy of the DPCD capabilities for this sink
- *
- * Returns: %True if the sink supports MST, %false otherwise
- */
-bool drm_dp_read_mst_cap(struct drm_dp_aux *aux,
-			 const u8 dpcd[DP_RECEIVER_CAP_SIZE])
-{
-	u8 mstm_cap;
-
-	if (dpcd[DP_DPCD_REV] < DP_DPCD_REV_12)
-		return false;
-
-	if (drm_dp_dpcd_readb(aux, DP_MSTM_CAP, &mstm_cap) != 1)
-		return false;
-
-	return mstm_cap & DP_MST_CAP;
-}
-EXPORT_SYMBOL(drm_dp_read_mst_cap);
-
-/**
- * drm_dp_mst_topology_mgr_set_mst() - Set the MST state for a topology manager
- * @mgr: manager to set state for
- * @mst_state: true to enable MST on this connector - false to disable.
- *
- * This is called by the driver when it detects an MST capable device plugged
- * into a DP MST capable port, or when a DP MST capable device is unplugged.
- */
-int drm_dp_mst_topology_mgr_set_mst(struct drm_dp_mst_topology_mgr *mgr, bool mst_state)
-{
-	int ret = 0;
-	struct drm_dp_mst_branch *mstb = NULL;
-
-	mutex_lock(&mgr->payload_lock);
-	mutex_lock(&mgr->lock);
-	if (mst_state == mgr->mst_state)
-		goto out_unlock;
-
-	mgr->mst_state = mst_state;
-	/* set the device into MST mode */
-	if (mst_state) {
-		struct drm_dp_payload reset_pay;
-		int lane_count;
-		int link_rate;
-
-		WARN_ON(mgr->mst_primary);
-
-		/* get dpcd info */
-		ret = drm_dp_read_dpcd_caps(mgr->aux, mgr->dpcd);
-		if (ret < 0) {
-			drm_dbg_kms(mgr->dev, "%s: failed to read DPCD, ret %d\n",
-				    mgr->aux->name, ret);
-			goto out_unlock;
-		}
-
-		lane_count = min_t(int, mgr->dpcd[2] & DP_MAX_LANE_COUNT_MASK, mgr->max_lane_count);
-		link_rate = min_t(int, drm_dp_bw_code_to_link_rate(mgr->dpcd[1]), mgr->max_link_rate);
-		mgr->pbn_div = drm_dp_get_vc_payload_bw(mgr,
-							link_rate,
-							lane_count);
-		if (mgr->pbn_div == 0) {
-			ret = -EINVAL;
-			goto out_unlock;
-		}
-
-		/* add initial branch device at LCT 1 */
-		mstb = drm_dp_add_mst_branch_device(1, NULL);
-		if (mstb == NULL) {
-			ret = -ENOMEM;
-			goto out_unlock;
-		}
-		mstb->mgr = mgr;
-
-		/* give this the main reference */
-		mgr->mst_primary = mstb;
-		drm_dp_mst_topology_get_mstb(mgr->mst_primary);
-
-		ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
-					 DP_MST_EN |
-					 DP_UP_REQ_EN |
-					 DP_UPSTREAM_IS_SRC);
-		if (ret < 0)
-			goto out_unlock;
-
-		reset_pay.start_slot = 0;
-		reset_pay.num_slots = 0x3f;
-		drm_dp_dpcd_write_payload(mgr, 0, &reset_pay);
-
-		queue_work(system_long_wq, &mgr->work);
-
-		ret = 0;
-	} else {
-		/* disable MST on the device */
-		mstb = mgr->mst_primary;
-		mgr->mst_primary = NULL;
-		/* this can fail if the device is gone */
-		drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL, 0);
-		ret = 0;
-		memset(mgr->payloads, 0,
-		       mgr->max_payloads * sizeof(mgr->payloads[0]));
-		memset(mgr->proposed_vcpis, 0,
-		       mgr->max_payloads * sizeof(mgr->proposed_vcpis[0]));
-		mgr->payload_mask = 0;
-		set_bit(0, &mgr->payload_mask);
-		mgr->vcpi_mask = 0;
-		mgr->payload_id_table_cleared = false;
-	}
-
-out_unlock:
-	mutex_unlock(&mgr->lock);
-	mutex_unlock(&mgr->payload_lock);
-	if (mstb)
-		drm_dp_mst_topology_put_mstb(mstb);
-	return ret;
-
-}
-EXPORT_SYMBOL(drm_dp_mst_topology_mgr_set_mst);
-
-static void
-drm_dp_mst_topology_mgr_invalidate_mstb(struct drm_dp_mst_branch *mstb)
-{
-	struct drm_dp_mst_port *port;
-
-	/* The link address will need to be re-sent on resume */
-	mstb->link_address_sent = false;
-
-	list_for_each_entry(port, &mstb->ports, next)
-		if (port->mstb)
-			drm_dp_mst_topology_mgr_invalidate_mstb(port->mstb);
-}
-
-/**
- * drm_dp_mst_topology_mgr_suspend() - suspend the MST manager
- * @mgr: manager to suspend
- *
- * This function tells the MST device that we can't handle UP messages
- * anymore. This should stop it from sending any since we are suspended.
- */
-void drm_dp_mst_topology_mgr_suspend(struct drm_dp_mst_topology_mgr *mgr)
-{
-	mutex_lock(&mgr->lock);
-	drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
-			   DP_MST_EN | DP_UPSTREAM_IS_SRC);
-	mutex_unlock(&mgr->lock);
-	flush_work(&mgr->up_req_work);
-	flush_work(&mgr->work);
-	flush_work(&mgr->delayed_destroy_work);
-
-	mutex_lock(&mgr->lock);
-	if (mgr->mst_state && mgr->mst_primary)
-		drm_dp_mst_topology_mgr_invalidate_mstb(mgr->mst_primary);
-	mutex_unlock(&mgr->lock);
-}
-EXPORT_SYMBOL(drm_dp_mst_topology_mgr_suspend);
-
-/**
- * drm_dp_mst_topology_mgr_resume() - resume the MST manager
- * @mgr: manager to resume
- * @sync: whether or not to perform topology reprobing synchronously
- *
- * This will fetch DPCD and see if the device is still there,
- * if it is, it will rewrite the MSTM control bits, and return.
- *
- * If the device fails this returns -1, and the driver should do
- * a full MST reprobe, in case we were undocked.
- *
- * During system resume (where it is assumed that the driver will be calling
- * drm_atomic_helper_resume()) this function should be called beforehand with
- * @sync set to true. In contexts like runtime resume where the driver is not
- * expected to be calling drm_atomic_helper_resume(), this function should be
- * called with @sync set to false in order to avoid deadlocking.
- *
- * Returns: -1 if the MST topology was removed while we were suspended, 0
- * otherwise.
- */
-int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr,
-				   bool sync)
-{
-	int ret;
-	u8 guid[16];
-
-	mutex_lock(&mgr->lock);
-	if (!mgr->mst_primary)
-		goto out_fail;
-
-	ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd,
-			       DP_RECEIVER_CAP_SIZE);
-	if (ret != DP_RECEIVER_CAP_SIZE) {
-		drm_dbg_kms(mgr->dev, "dpcd read failed - undocked during suspend?\n");
-		goto out_fail;
-	}
-
-	ret = drm_dp_dpcd_writeb(mgr->aux, DP_MSTM_CTRL,
-				 DP_MST_EN |
-				 DP_UP_REQ_EN |
-				 DP_UPSTREAM_IS_SRC);
-	if (ret < 0) {
-		drm_dbg_kms(mgr->dev, "mst write failed - undocked during suspend?\n");
-		goto out_fail;
-	}
-
-	/* Some hubs forget their guids after they resume */
-	ret = drm_dp_dpcd_read(mgr->aux, DP_GUID, guid, 16);
-	if (ret != 16) {
-		drm_dbg_kms(mgr->dev, "dpcd read failed - undocked during suspend?\n");
-		goto out_fail;
-	}
-
-	ret = drm_dp_check_mstb_guid(mgr->mst_primary, guid);
-	if (ret) {
-		drm_dbg_kms(mgr->dev, "check mstb failed - undocked during suspend?\n");
-		goto out_fail;
-	}
-
-	/*
-	 * For the final step of resuming the topology, we need to bring the
-	 * state of our in-memory topology back into sync with reality. So,
-	 * restart the probing process as if we're probing a new hub
-	 */
-	queue_work(system_long_wq, &mgr->work);
-	mutex_unlock(&mgr->lock);
-
-	if (sync) {
-		drm_dbg_kms(mgr->dev,
-			    "Waiting for link probe work to finish re-syncing topology...\n");
-		flush_work(&mgr->work);
-	}
-
-	return 0;
-
-out_fail:
-	mutex_unlock(&mgr->lock);
-	return -1;
-}
-EXPORT_SYMBOL(drm_dp_mst_topology_mgr_resume);
-
-static bool
-drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up,
-		      struct drm_dp_mst_branch **mstb)
-{
-	int len;
-	u8 replyblock[32];
-	int replylen, curreply;
-	int ret;
-	u8 hdrlen;
-	struct drm_dp_sideband_msg_hdr hdr;
-	struct drm_dp_sideband_msg_rx *msg =
-		up ? &mgr->up_req_recv : &mgr->down_rep_recv;
-	int basereg = up ? DP_SIDEBAND_MSG_UP_REQ_BASE :
-			   DP_SIDEBAND_MSG_DOWN_REP_BASE;
-
-	if (!up)
-		*mstb = NULL;
-
-	len = min(mgr->max_dpcd_transaction_bytes, 16);
-	ret = drm_dp_dpcd_read(mgr->aux, basereg, replyblock, len);
-	if (ret != len) {
-		drm_dbg_kms(mgr->dev, "failed to read DPCD down rep %d %d\n", len, ret);
-		return false;
-	}
-
-	ret = drm_dp_decode_sideband_msg_hdr(mgr, &hdr, replyblock, len, &hdrlen);
-	if (ret == false) {
-		print_hex_dump(KERN_DEBUG, "failed hdr", DUMP_PREFIX_NONE, 16,
-			       1, replyblock, len, false);
-		drm_dbg_kms(mgr->dev, "ERROR: failed header\n");
-		return false;
-	}
-
-	if (!up) {
-		/* Caller is responsible for giving back this reference */
-		*mstb = drm_dp_get_mst_branch_device(mgr, hdr.lct, hdr.rad);
-		if (!*mstb) {
-			drm_dbg_kms(mgr->dev, "Got MST reply from unknown device %d\n", hdr.lct);
-			return false;
-		}
-	}
-
-	if (!drm_dp_sideband_msg_set_header(msg, &hdr, hdrlen)) {
-		drm_dbg_kms(mgr->dev, "sideband msg set header failed %d\n", replyblock[0]);
-		return false;
-	}
-
-	replylen = min(msg->curchunk_len, (u8)(len - hdrlen));
-	ret = drm_dp_sideband_append_payload(msg, replyblock + hdrlen, replylen);
-	if (!ret) {
-		drm_dbg_kms(mgr->dev, "sideband msg build failed %d\n", replyblock[0]);
-		return false;
-	}
-
-	replylen = msg->curchunk_len + msg->curchunk_hdrlen - len;
-	curreply = len;
-	while (replylen > 0) {
-		len = min3(replylen, mgr->max_dpcd_transaction_bytes, 16);
-		ret = drm_dp_dpcd_read(mgr->aux, basereg + curreply,
-				    replyblock, len);
-		if (ret != len) {
-			drm_dbg_kms(mgr->dev, "failed to read a chunk (len %d, ret %d)\n",
-				    len, ret);
-			return false;
-		}
-
-		ret = drm_dp_sideband_append_payload(msg, replyblock, len);
-		if (!ret) {
-			drm_dbg_kms(mgr->dev, "failed to build sideband msg\n");
-			return false;
-		}
-
-		curreply += len;
-		replylen -= len;
-	}
-	return true;
-}
-
-static int drm_dp_mst_handle_down_rep(struct drm_dp_mst_topology_mgr *mgr)
-{
-	struct drm_dp_sideband_msg_tx *txmsg;
-	struct drm_dp_mst_branch *mstb = NULL;
-	struct drm_dp_sideband_msg_rx *msg = &mgr->down_rep_recv;
-
-	if (!drm_dp_get_one_sb_msg(mgr, false, &mstb))
-		goto out;
-
-	/* Multi-packet message transmission, don't clear the reply */
-	if (!msg->have_eomt)
-		goto out;
-
-	/* find the message */
-	mutex_lock(&mgr->qlock);
-	txmsg = list_first_entry_or_null(&mgr->tx_msg_downq,
-					 struct drm_dp_sideband_msg_tx, next);
-	mutex_unlock(&mgr->qlock);
-
-	/* Were we actually expecting a response, and from this mstb? */
-	if (!txmsg || txmsg->dst != mstb) {
-		struct drm_dp_sideband_msg_hdr *hdr;
-
-		hdr = &msg->initial_hdr;
-		drm_dbg_kms(mgr->dev, "Got MST reply with no msg %p %d %d %02x %02x\n",
-			    mstb, hdr->seqno, hdr->lct, hdr->rad[0], msg->msg[0]);
-		goto out_clear_reply;
-	}
-
-	drm_dp_sideband_parse_reply(mgr, msg, &txmsg->reply);
-
-	if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
-		drm_dbg_kms(mgr->dev,
-			    "Got NAK reply: req 0x%02x (%s), reason 0x%02x (%s), nak data 0x%02x\n",
-			    txmsg->reply.req_type,
-			    drm_dp_mst_req_type_str(txmsg->reply.req_type),
-			    txmsg->reply.u.nak.reason,
-			    drm_dp_mst_nak_reason_str(txmsg->reply.u.nak.reason),
-			    txmsg->reply.u.nak.nak_data);
-	}
-
-	memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
-	drm_dp_mst_topology_put_mstb(mstb);
-
-	mutex_lock(&mgr->qlock);
-	txmsg->state = DRM_DP_SIDEBAND_TX_RX;
-	list_del(&txmsg->next);
-	mutex_unlock(&mgr->qlock);
-
-	wake_up_all(&mgr->tx_waitq);
-
-	return 0;
-
-out_clear_reply:
-	memset(msg, 0, sizeof(struct drm_dp_sideband_msg_rx));
-out:
-	if (mstb)
-		drm_dp_mst_topology_put_mstb(mstb);
-
-	return 0;
-}
-
-static inline bool
-drm_dp_mst_process_up_req(struct drm_dp_mst_topology_mgr *mgr,
-			  struct drm_dp_pending_up_req *up_req)
-{
-	struct drm_dp_mst_branch *mstb = NULL;
-	struct drm_dp_sideband_msg_req_body *msg = &up_req->msg;
-	struct drm_dp_sideband_msg_hdr *hdr = &up_req->hdr;
-	bool hotplug = false;
-
-	if (hdr->broadcast) {
-		const u8 *guid = NULL;
-
-		if (msg->req_type == DP_CONNECTION_STATUS_NOTIFY)
-			guid = msg->u.conn_stat.guid;
-		else if (msg->req_type == DP_RESOURCE_STATUS_NOTIFY)
-			guid = msg->u.resource_stat.guid;
-
-		if (guid)
-			mstb = drm_dp_get_mst_branch_device_by_guid(mgr, guid);
-	} else {
-		mstb = drm_dp_get_mst_branch_device(mgr, hdr->lct, hdr->rad);
-	}
-
-	if (!mstb) {
-		drm_dbg_kms(mgr->dev, "Got MST reply from unknown device %d\n", hdr->lct);
-		return false;
-	}
-
-	/* TODO: Add missing handler for DP_RESOURCE_STATUS_NOTIFY events */
-	if (msg->req_type == DP_CONNECTION_STATUS_NOTIFY) {
-		drm_dp_mst_handle_conn_stat(mstb, &msg->u.conn_stat);
-		hotplug = true;
-	}
-
-	drm_dp_mst_topology_put_mstb(mstb);
-	return hotplug;
-}
-
-static void drm_dp_mst_up_req_work(struct work_struct *work)
-{
-	struct drm_dp_mst_topology_mgr *mgr =
-		container_of(work, struct drm_dp_mst_topology_mgr,
-			     up_req_work);
-	struct drm_dp_pending_up_req *up_req;
-	bool send_hotplug = false;
-
-	mutex_lock(&mgr->probe_lock);
-	while (true) {
-		mutex_lock(&mgr->up_req_lock);
-		up_req = list_first_entry_or_null(&mgr->up_req_list,
-						  struct drm_dp_pending_up_req,
-						  next);
-		if (up_req)
-			list_del(&up_req->next);
-		mutex_unlock(&mgr->up_req_lock);
-
-		if (!up_req)
-			break;
-
-		send_hotplug |= drm_dp_mst_process_up_req(mgr, up_req);
-		kfree(up_req);
-	}
-	mutex_unlock(&mgr->probe_lock);
-
-	if (send_hotplug)
-		drm_kms_helper_hotplug_event(mgr->dev);
-}
-
-static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr)
-{
-	struct drm_dp_pending_up_req *up_req;
-
-	if (!drm_dp_get_one_sb_msg(mgr, true, NULL))
-		goto out;
-
-	if (!mgr->up_req_recv.have_eomt)
-		return 0;
-
-	up_req = kzalloc(sizeof(*up_req), GFP_KERNEL);
-	if (!up_req)
-		return -ENOMEM;
-
-	INIT_LIST_HEAD(&up_req->next);
-
-	drm_dp_sideband_parse_req(mgr, &mgr->up_req_recv, &up_req->msg);
-
-	if (up_req->msg.req_type != DP_CONNECTION_STATUS_NOTIFY &&
-	    up_req->msg.req_type != DP_RESOURCE_STATUS_NOTIFY) {
-		drm_dbg_kms(mgr->dev, "Received unknown up req type, ignoring: %x\n",
-			    up_req->msg.req_type);
-		kfree(up_req);
-		goto out;
-	}
-
-	drm_dp_send_up_ack_reply(mgr, mgr->mst_primary, up_req->msg.req_type,
-				 false);
-
-	if (up_req->msg.req_type == DP_CONNECTION_STATUS_NOTIFY) {
-		const struct drm_dp_connection_status_notify *conn_stat =
-			&up_req->msg.u.conn_stat;
-
-		drm_dbg_kms(mgr->dev, "Got CSN: pn: %d ldps:%d ddps: %d mcs: %d ip: %d pdt: %d\n",
-			    conn_stat->port_number,
-			    conn_stat->legacy_device_plug_status,
-			    conn_stat->displayport_device_plug_status,
-			    conn_stat->message_capability_status,
-			    conn_stat->input_port,
-			    conn_stat->peer_device_type);
-	} else if (up_req->msg.req_type == DP_RESOURCE_STATUS_NOTIFY) {
-		const struct drm_dp_resource_status_notify *res_stat =
-			&up_req->msg.u.resource_stat;
-
-		drm_dbg_kms(mgr->dev, "Got RSN: pn: %d avail_pbn %d\n",
-			    res_stat->port_number,
-			    res_stat->available_pbn);
-	}
-
-	up_req->hdr = mgr->up_req_recv.initial_hdr;
-	mutex_lock(&mgr->up_req_lock);
-	list_add_tail(&up_req->next, &mgr->up_req_list);
-	mutex_unlock(&mgr->up_req_lock);
-	queue_work(system_long_wq, &mgr->up_req_work);
-
-out:
-	memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx));
-	return 0;
-}
-
-/**
- * drm_dp_mst_hpd_irq() - MST hotplug IRQ notify
- * @mgr: manager to notify irq for.
- * @esi: 4 bytes from SINK_COUNT_ESI
- * @handled: whether the hpd interrupt was consumed or not
- *
- * This should be called from the driver when it detects a short IRQ,
- * along with the value of the DEVICE_SERVICE_IRQ_VECTOR_ESI0. The
- * topology manager will process the sideband messages received as a result
- * of this.
- */
-int drm_dp_mst_hpd_irq(struct drm_dp_mst_topology_mgr *mgr, u8 *esi, bool *handled)
-{
-	int ret = 0;
-	int sc;
-	*handled = false;
-	sc = DP_GET_SINK_COUNT(esi[0]);
-
-	if (sc != mgr->sink_count) {
-		mgr->sink_count = sc;
-		*handled = true;
-	}
-
-	if (esi[1] & DP_DOWN_REP_MSG_RDY) {
-		ret = drm_dp_mst_handle_down_rep(mgr);
-		*handled = true;
-	}
-
-	if (esi[1] & DP_UP_REQ_MSG_RDY) {
-		ret |= drm_dp_mst_handle_up_req(mgr);
-		*handled = true;
-	}
-
-	drm_dp_mst_kick_tx(mgr);
-	return ret;
-}
-EXPORT_SYMBOL(drm_dp_mst_hpd_irq);
-
-/**
- * drm_dp_mst_detect_port() - get connection status for an MST port
- * @connector: DRM connector for this port
- * @ctx: The acquisition context to use for grabbing locks
- * @mgr: manager for this port
- * @port: pointer to a port
- *
- * This returns the current connection state for a port.
- */
-int
-drm_dp_mst_detect_port(struct drm_connector *connector,
-		       struct drm_modeset_acquire_ctx *ctx,
-		       struct drm_dp_mst_topology_mgr *mgr,
-		       struct drm_dp_mst_port *port)
-{
-	int ret;
-
-	/* we need to search for the port in the mgr in case it's gone */
-	port = drm_dp_mst_topology_get_port_validated(mgr, port);
-	if (!port)
-		return connector_status_disconnected;
-
-	ret = drm_modeset_lock(&mgr->base.lock, ctx);
-	if (ret)
-		goto out;
-
-	ret = connector_status_disconnected;
-
-	if (!port->ddps)
-		goto out;
-
-	switch (port->pdt) {
-	case DP_PEER_DEVICE_NONE:
-		break;
-	case DP_PEER_DEVICE_MST_BRANCHING:
-		if (!port->mcs)
-			ret = connector_status_connected;
-		break;
-
-	case DP_PEER_DEVICE_SST_SINK:
-		ret = connector_status_connected;
-		/* for logical ports - cache the EDID */
-		if (port->port_num >= DP_MST_LOGICAL_PORT_0 && !port->cached_edid)
-			port->cached_edid = drm_get_edid(connector, &port->aux.ddc);
-		break;
-	case DP_PEER_DEVICE_DP_LEGACY_CONV:
-		if (port->ldps)
-			ret = connector_status_connected;
-		break;
-	}
-out:
-	drm_dp_mst_topology_put_port(port);
-	return ret;
-}
-EXPORT_SYMBOL(drm_dp_mst_detect_port);
-
-/**
- * drm_dp_mst_get_edid() - get EDID for an MST port
- * @connector: toplevel connector to get EDID for
- * @mgr: manager for this port
- * @port: unverified pointer to a port.
- *
- * This returns an EDID for the port connected to a connector,
- * It validates the pointer still exists so the caller doesn't require a
- * reference.
- */
-struct edid *drm_dp_mst_get_edid(struct drm_connector *connector, struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
-{
-	struct edid *edid = NULL;
-
-	/* we need to search for the port in the mgr in case it's gone */
-	port = drm_dp_mst_topology_get_port_validated(mgr, port);
-	if (!port)
-		return NULL;
-
-	if (port->cached_edid)
-		edid = drm_edid_duplicate(port->cached_edid);
-	else {
-		edid = drm_get_edid(connector, &port->aux.ddc);
-	}
-	port->has_audio = drm_detect_monitor_audio(edid);
-	drm_dp_mst_topology_put_port(port);
-	return edid;
-}
-EXPORT_SYMBOL(drm_dp_mst_get_edid);
-
-/**
- * drm_dp_find_vcpi_slots() - Find VCPI slots for this PBN value
- * @mgr: manager to use
- * @pbn: payload bandwidth to convert into slots.
- *
- * Calculate the number of VCPI slots that will be required for the given PBN
- * value. This function is deprecated, and should not be used in atomic
- * drivers.
- *
- * RETURNS:
- * The total slots required for this port, or error.
- */
-int drm_dp_find_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr,
-			   int pbn)
-{
-	int num_slots;
-
-	num_slots = DIV_ROUND_UP(pbn, mgr->pbn_div);
-
-	/* max. time slots - one slot for MTP header */
-	if (num_slots > 63)
-		return -ENOSPC;
-	return num_slots;
-}
-EXPORT_SYMBOL(drm_dp_find_vcpi_slots);
-
-static int drm_dp_init_vcpi(struct drm_dp_mst_topology_mgr *mgr,
-			    struct drm_dp_vcpi *vcpi, int pbn, int slots)
-{
-	int ret;
-
-	vcpi->pbn = pbn;
-	vcpi->aligned_pbn = slots * mgr->pbn_div;
-	vcpi->num_slots = slots;
-
-	ret = drm_dp_mst_assign_payload_id(mgr, vcpi);
-	if (ret < 0)
-		return ret;
-	return 0;
-}
-
-/**
- * drm_dp_atomic_find_vcpi_slots() - Find and add VCPI slots to the state
- * @state: global atomic state
- * @mgr: MST topology manager for the port
- * @port: port to find vcpi slots for
- * @pbn: bandwidth required for the mode in PBN
- * @pbn_div: divider for DSC mode that takes FEC into account
- *
- * Allocates VCPI slots to @port, replacing any previous VCPI allocations it
- * may have had. Any atomic drivers which support MST must call this function
- * in their &drm_encoder_helper_funcs.atomic_check() callback to change the
- * current VCPI allocation for the new state, but only when
- * &drm_crtc_state.mode_changed or &drm_crtc_state.connectors_changed is set
- * to ensure compatibility with userspace applications that still use the
- * legacy modesetting UAPI.
- *
- * Allocations set by this function are not checked against the bandwidth
- * restraints of @mgr until the driver calls drm_dp_mst_atomic_check().
- *
- * Additionally, it is OK to call this function multiple times on the same
- * @port as needed. It is not OK however, to call this function and
- * drm_dp_atomic_release_vcpi_slots() in the same atomic check phase.
- *
- * See also:
- * drm_dp_atomic_release_vcpi_slots()
- * drm_dp_mst_atomic_check()
- *
- * Returns:
- * Total slots in the atomic state assigned for this port, or a negative error
- * code if the port no longer exists
- */
-int drm_dp_atomic_find_vcpi_slots(struct drm_atomic_state *state,
-				  struct drm_dp_mst_topology_mgr *mgr,
-				  struct drm_dp_mst_port *port, int pbn,
-				  int pbn_div)
-{
-	struct drm_dp_mst_topology_state *topology_state;
-	struct drm_dp_vcpi_allocation *pos, *vcpi = NULL;
-	int prev_slots, prev_bw, req_slots;
-
-	topology_state = drm_atomic_get_mst_topology_state(state, mgr);
-	if (IS_ERR(topology_state))
-		return PTR_ERR(topology_state);
-
-	/* Find the current allocation for this port, if any */
-	list_for_each_entry(pos, &topology_state->vcpis, next) {
-		if (pos->port == port) {
-			vcpi = pos;
-			prev_slots = vcpi->vcpi;
-			prev_bw = vcpi->pbn;
-
-			/*
-			 * This should never happen, unless the driver tries
-			 * releasing and allocating the same VCPI allocation,
-			 * which is an error
-			 */
-			if (WARN_ON(!prev_slots)) {
-				drm_err(mgr->dev,
-					"cannot allocate and release VCPI on [MST PORT:%p] in the same state\n",
-					port);
-				return -EINVAL;
-			}
-
-			break;
-		}
-	}
-	if (!vcpi) {
-		prev_slots = 0;
-		prev_bw = 0;
-	}
-
-	if (pbn_div <= 0)
-		pbn_div = mgr->pbn_div;
-
-	req_slots = DIV_ROUND_UP(pbn, pbn_div);
-
-	drm_dbg_atomic(mgr->dev, "[CONNECTOR:%d:%s] [MST PORT:%p] VCPI %d -> %d\n",
-		       port->connector->base.id, port->connector->name,
-		       port, prev_slots, req_slots);
-	drm_dbg_atomic(mgr->dev, "[CONNECTOR:%d:%s] [MST PORT:%p] PBN %d -> %d\n",
-		       port->connector->base.id, port->connector->name,
-		       port, prev_bw, pbn);
-
-	/* Add the new allocation to the state */
-	if (!vcpi) {
-		vcpi = kzalloc(sizeof(*vcpi), GFP_KERNEL);
-		if (!vcpi)
-			return -ENOMEM;
-
-		drm_dp_mst_get_port_malloc(port);
-		vcpi->port = port;
-		list_add(&vcpi->next, &topology_state->vcpis);
-	}
-	vcpi->vcpi = req_slots;
-	vcpi->pbn = pbn;
-
-	return req_slots;
-}
-EXPORT_SYMBOL(drm_dp_atomic_find_vcpi_slots);
-
-/**
- * drm_dp_atomic_release_vcpi_slots() - Release allocated vcpi slots
- * @state: global atomic state
- * @mgr: MST topology manager for the port
- * @port: The port to release the VCPI slots from
- *
- * Releases any VCPI slots that have been allocated to a port in the atomic
- * state. Any atomic drivers which support MST must call this function in
- * their &drm_connector_helper_funcs.atomic_check() callback when the
- * connector will no longer have VCPI allocated (e.g. because its CRTC was
- * removed) when it had VCPI allocated in the previous atomic state.
- *
- * It is OK to call this even if @port has been removed from the system.
- * Additionally, it is OK to call this function multiple times on the same
- * @port as needed. It is not OK however, to call this function and
- * drm_dp_atomic_find_vcpi_slots() on the same @port in a single atomic check
- * phase.
- *
- * See also:
- * drm_dp_atomic_find_vcpi_slots()
- * drm_dp_mst_atomic_check()
- *
- * Returns:
- * 0 if all slots for this port were added back to
- * &drm_dp_mst_topology_state.avail_slots or negative error code
- */
-int drm_dp_atomic_release_vcpi_slots(struct drm_atomic_state *state,
-				     struct drm_dp_mst_topology_mgr *mgr,
-				     struct drm_dp_mst_port *port)
-{
-	struct drm_dp_mst_topology_state *topology_state;
-	struct drm_dp_vcpi_allocation *pos;
-	bool found = false;
-
-	topology_state = drm_atomic_get_mst_topology_state(state, mgr);
-	if (IS_ERR(topology_state))
-		return PTR_ERR(topology_state);
-
-	list_for_each_entry(pos, &topology_state->vcpis, next) {
-		if (pos->port == port) {
-			found = true;
-			break;
-		}
-	}
-	if (WARN_ON(!found)) {
-		drm_err(mgr->dev, "no VCPI for [MST PORT:%p] found in mst state %p\n",
-			port, &topology_state->base);
-		return -EINVAL;
-	}
-
-	drm_dbg_atomic(mgr->dev, "[MST PORT:%p] VCPI %d -> 0\n", port, pos->vcpi);
-	if (pos->vcpi) {
-		drm_dp_mst_put_port_malloc(port);
-		pos->vcpi = 0;
-		pos->pbn = 0;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL(drm_dp_atomic_release_vcpi_slots);
-
-/**
- * drm_dp_mst_update_slots() - updates the slot info depending on the DP ecoding format
- * @mst_state: mst_state to update
- * @link_encoding_cap: the ecoding format on the link
- */
-void drm_dp_mst_update_slots(struct drm_dp_mst_topology_state *mst_state, uint8_t link_encoding_cap)
-{
-	if (link_encoding_cap == DP_CAP_ANSI_128B132B) {
-		mst_state->total_avail_slots = 64;
-		mst_state->start_slot = 0;
-	} else {
-		mst_state->total_avail_slots = 63;
-		mst_state->start_slot = 1;
-	}
-
-	DRM_DEBUG_KMS("%s encoding format on mst_state 0x%p\n",
-		      (link_encoding_cap == DP_CAP_ANSI_128B132B) ? "128b/132b":"8b/10b",
-		      mst_state);
-}
-EXPORT_SYMBOL(drm_dp_mst_update_slots);
-
-/**
- * drm_dp_mst_allocate_vcpi() - Allocate a virtual channel
- * @mgr: manager for this port
- * @port: port to allocate a virtual channel for.
- * @pbn: payload bandwidth number to request
- * @slots: returned number of slots for this PBN.
- */
-bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
-			      struct drm_dp_mst_port *port, int pbn, int slots)
-{
-	int ret;
-
-	if (slots < 0)
-		return false;
-
-	port = drm_dp_mst_topology_get_port_validated(mgr, port);
-	if (!port)
-		return false;
-
-	if (port->vcpi.vcpi > 0) {
-		drm_dbg_kms(mgr->dev,
-			    "payload: vcpi %d already allocated for pbn %d - requested pbn %d\n",
-			    port->vcpi.vcpi, port->vcpi.pbn, pbn);
-		if (pbn == port->vcpi.pbn) {
-			drm_dp_mst_topology_put_port(port);
-			return true;
-		}
-	}
-
-	ret = drm_dp_init_vcpi(mgr, &port->vcpi, pbn, slots);
-	if (ret) {
-		drm_dbg_kms(mgr->dev, "failed to init vcpi slots=%d ret=%d\n",
-			    DIV_ROUND_UP(pbn, mgr->pbn_div), ret);
-		drm_dp_mst_topology_put_port(port);
-		goto out;
-	}
-	drm_dbg_kms(mgr->dev, "initing vcpi for pbn=%d slots=%d\n", pbn, port->vcpi.num_slots);
-
-	/* Keep port allocated until its payload has been removed */
-	drm_dp_mst_get_port_malloc(port);
-	drm_dp_mst_topology_put_port(port);
-	return true;
-out:
-	return false;
-}
-EXPORT_SYMBOL(drm_dp_mst_allocate_vcpi);
-
-int drm_dp_mst_get_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
-{
-	int slots = 0;
-
-	port = drm_dp_mst_topology_get_port_validated(mgr, port);
-	if (!port)
-		return slots;
-
-	slots = port->vcpi.num_slots;
-	drm_dp_mst_topology_put_port(port);
-	return slots;
-}
-EXPORT_SYMBOL(drm_dp_mst_get_vcpi_slots);
-
-/**
- * drm_dp_mst_reset_vcpi_slots() - Reset number of slots to 0 for VCPI
- * @mgr: manager for this port
- * @port: unverified pointer to a port.
- *
- * This just resets the number of slots for the ports VCPI for later programming.
- */
-void drm_dp_mst_reset_vcpi_slots(struct drm_dp_mst_topology_mgr *mgr, struct drm_dp_mst_port *port)
-{
-	/*
-	 * A port with VCPI will remain allocated until its VCPI is
-	 * released, no verified ref needed
-	 */
-
-	port->vcpi.num_slots = 0;
-}
-EXPORT_SYMBOL(drm_dp_mst_reset_vcpi_slots);
-
-/**
- * drm_dp_mst_deallocate_vcpi() - deallocate a VCPI
- * @mgr: manager for this port
- * @port: port to deallocate vcpi for
- *
- * This can be called unconditionally, regardless of whether
- * drm_dp_mst_allocate_vcpi() succeeded or not.
- */
-void drm_dp_mst_deallocate_vcpi(struct drm_dp_mst_topology_mgr *mgr,
-				struct drm_dp_mst_port *port)
-{
-	bool skip;
-
-	if (!port->vcpi.vcpi)
-		return;
-
-	mutex_lock(&mgr->lock);
-	skip = !drm_dp_mst_port_downstream_of_branch(port, mgr->mst_primary);
-	mutex_unlock(&mgr->lock);
-
-	if (skip)
-		return;
-
-	drm_dp_mst_put_payload_id(mgr, port->vcpi.vcpi);
-	port->vcpi.num_slots = 0;
-	port->vcpi.pbn = 0;
-	port->vcpi.aligned_pbn = 0;
-	port->vcpi.vcpi = 0;
-	drm_dp_mst_put_port_malloc(port);
-}
-EXPORT_SYMBOL(drm_dp_mst_deallocate_vcpi);
-
-static int drm_dp_dpcd_write_payload(struct drm_dp_mst_topology_mgr *mgr,
-				     int id, struct drm_dp_payload *payload)
-{
-	u8 payload_alloc[3], status;
-	int ret;
-	int retries = 0;
-
-	drm_dp_dpcd_writeb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS,
-			   DP_PAYLOAD_TABLE_UPDATED);
-
-	payload_alloc[0] = id;
-	payload_alloc[1] = payload->start_slot;
-	payload_alloc[2] = payload->num_slots;
-
-	ret = drm_dp_dpcd_write(mgr->aux, DP_PAYLOAD_ALLOCATE_SET, payload_alloc, 3);
-	if (ret != 3) {
-		drm_dbg_kms(mgr->dev, "failed to write payload allocation %d\n", ret);
-		goto fail;
-	}
-
-retry:
-	ret = drm_dp_dpcd_readb(mgr->aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
-	if (ret < 0) {
-		drm_dbg_kms(mgr->dev, "failed to read payload table status %d\n", ret);
-		goto fail;
-	}
-
-	if (!(status & DP_PAYLOAD_TABLE_UPDATED)) {
-		retries++;
-		if (retries < 20) {
-			usleep_range(10000, 20000);
-			goto retry;
-		}
-		drm_dbg_kms(mgr->dev, "status not set after read payload table status %d\n",
-			    status);
-		ret = -EINVAL;
-		goto fail;
-	}
-	ret = 0;
-fail:
-	return ret;
-}
-
-static int do_get_act_status(struct drm_dp_aux *aux)
-{
-	int ret;
-	u8 status;
-
-	ret = drm_dp_dpcd_readb(aux, DP_PAYLOAD_TABLE_UPDATE_STATUS, &status);
-	if (ret < 0)
-		return ret;
-
-	return status;
-}
-
-/**
- * drm_dp_check_act_status() - Polls for ACT handled status.
- * @mgr: manager to use
- *
- * Tries waiting for the MST hub to finish updating it's payload table by
- * polling for the ACT handled bit for up to 3 seconds (yes-some hubs really
- * take that long).
- *
- * Returns:
- * 0 if the ACT was handled in time, negative error code on failure.
- */
-int drm_dp_check_act_status(struct drm_dp_mst_topology_mgr *mgr)
-{
-	/*
-	 * There doesn't seem to be any recommended retry count or timeout in
-	 * the MST specification. Since some hubs have been observed to take
-	 * over 1 second to update their payload allocations under certain
-	 * conditions, we use a rather large timeout value.
-	 */
-	const int timeout_ms = 3000;
-	int ret, status;
-
-	ret = readx_poll_timeout(do_get_act_status, mgr->aux, status,
-				 status & DP_PAYLOAD_ACT_HANDLED || status < 0,
-				 200, timeout_ms * USEC_PER_MSEC);
-	if (ret < 0 && status >= 0) {
-		drm_err(mgr->dev, "Failed to get ACT after %dms, last status: %02x\n",
-			timeout_ms, status);
-		return -EINVAL;
-	} else if (status < 0) {
-		/*
-		 * Failure here isn't unexpected - the hub may have
-		 * just been unplugged
-		 */
-		drm_dbg_kms(mgr->dev, "Failed to read payload table status: %d\n", status);
-		return status;
-	}
-
-	return 0;
-}
-EXPORT_SYMBOL(drm_dp_check_act_status);
-
-/**
- * drm_dp_calc_pbn_mode() - Calculate the PBN for a mode.
- * @clock: dot clock for the mode
- * @bpp: bpp for the mode.
- * @dsc: DSC mode. If true, bpp has units of 1/16 of a bit per pixel
- *
- * This uses the formula in the spec to calculate the PBN value for a mode.
- */
-int drm_dp_calc_pbn_mode(int clock, int bpp, bool dsc)
-{
-	/*
-	 * margin 5300ppm + 300ppm ~ 0.6% as per spec, factor is 1.006
-	 * The unit of 54/64Mbytes/sec is an arbitrary unit chosen based on
-	 * common multiplier to render an integer PBN for all link rate/lane
-	 * counts combinations
-	 * calculate
-	 * peak_kbps *= (1006/1000)
-	 * peak_kbps *= (64/54)
-	 * peak_kbps *= 8    convert to bytes
-	 *
-	 * If the bpp is in units of 1/16, further divide by 16. Put this
-	 * factor in the numerator rather than the denominator to avoid
-	 * integer overflow
-	 */
-
-	if (dsc)
-		return DIV_ROUND_UP_ULL(mul_u32_u32(clock * (bpp / 16), 64 * 1006),
-					8 * 54 * 1000 * 1000);
-
-	return DIV_ROUND_UP_ULL(mul_u32_u32(clock * bpp, 64 * 1006),
-				8 * 54 * 1000 * 1000);
-}
-EXPORT_SYMBOL(drm_dp_calc_pbn_mode);
-
-/* we want to kick the TX after we've ack the up/down IRQs. */
-static void drm_dp_mst_kick_tx(struct drm_dp_mst_topology_mgr *mgr)
-{
-	queue_work(system_long_wq, &mgr->tx_work);
-}
-
-/*
- * Helper function for parsing DP device types into convenient strings
- * for use with dp_mst_topology
- */
-static const char *pdt_to_string(u8 pdt)
-{
-	switch (pdt) {
-	case DP_PEER_DEVICE_NONE:
-		return "NONE";
-	case DP_PEER_DEVICE_SOURCE_OR_SST:
-		return "SOURCE OR SST";
-	case DP_PEER_DEVICE_MST_BRANCHING:
-		return "MST BRANCHING";
-	case DP_PEER_DEVICE_SST_SINK:
-		return "SST SINK";
-	case DP_PEER_DEVICE_DP_LEGACY_CONV:
-		return "DP LEGACY CONV";
-	default:
-		return "ERR";
-	}
-}
-
-static void drm_dp_mst_dump_mstb(struct seq_file *m,
-				 struct drm_dp_mst_branch *mstb)
-{
-	struct drm_dp_mst_port *port;
-	int tabs = mstb->lct;
-	char prefix[10];
-	int i;
-
-	for (i = 0; i < tabs; i++)
-		prefix[i] = '\t';
-	prefix[i] = '\0';
-
-	seq_printf(m, "%smstb - [%p]: num_ports: %d\n", prefix, mstb, mstb->num_ports);
-	list_for_each_entry(port, &mstb->ports, next) {
-		seq_printf(m, "%sport %d - [%p] (%s - %s): ddps: %d, ldps: %d, sdp: %d/%d, fec: %s, conn: %p\n",
-			   prefix,
-			   port->port_num,
-			   port,
-			   port->input ? "input" : "output",
-			   pdt_to_string(port->pdt),
-			   port->ddps,
-			   port->ldps,
-			   port->num_sdp_streams,
-			   port->num_sdp_stream_sinks,
-			   port->fec_capable ? "true" : "false",
-			   port->connector);
-		if (port->mstb)
-			drm_dp_mst_dump_mstb(m, port->mstb);
-	}
-}
-
-#define DP_PAYLOAD_TABLE_SIZE		64
-
-static bool dump_dp_payload_table(struct drm_dp_mst_topology_mgr *mgr,
-				  char *buf)
-{
-	int i;
-
-	for (i = 0; i < DP_PAYLOAD_TABLE_SIZE; i += 16) {
-		if (drm_dp_dpcd_read(mgr->aux,
-				     DP_PAYLOAD_TABLE_UPDATE_STATUS + i,
-				     &buf[i], 16) != 16)
-			return false;
-	}
-	return true;
-}
-
-static void fetch_monitor_name(struct drm_dp_mst_topology_mgr *mgr,
-			       struct drm_dp_mst_port *port, char *name,
-			       int namelen)
-{
-	struct edid *mst_edid;
-
-	mst_edid = drm_dp_mst_get_edid(port->connector, mgr, port);
-	drm_edid_get_monitor_name(mst_edid, name, namelen);
-}
-
-/**
- * drm_dp_mst_dump_topology(): dump topology to seq file.
- * @m: seq_file to dump output to
- * @mgr: manager to dump current topology for.
- *
- * helper to dump MST topology to a seq file for debugfs.
- */
-void drm_dp_mst_dump_topology(struct seq_file *m,
-			      struct drm_dp_mst_topology_mgr *mgr)
-{
-	int i;
-	struct drm_dp_mst_port *port;
-
-	mutex_lock(&mgr->lock);
-	if (mgr->mst_primary)
-		drm_dp_mst_dump_mstb(m, mgr->mst_primary);
-
-	/* dump VCPIs */
-	mutex_unlock(&mgr->lock);
-
-	mutex_lock(&mgr->payload_lock);
-	seq_printf(m, "\n*** VCPI Info ***\n");
-	seq_printf(m, "payload_mask: %lx, vcpi_mask: %lx, max_payloads: %d\n", mgr->payload_mask, mgr->vcpi_mask, mgr->max_payloads);
-
-	seq_printf(m, "\n|   idx   |  port # |  vcp_id | # slots |     sink name     |\n");
-	for (i = 0; i < mgr->max_payloads; i++) {
-		if (mgr->proposed_vcpis[i]) {
-			char name[14];
-
-			port = container_of(mgr->proposed_vcpis[i], struct drm_dp_mst_port, vcpi);
-			fetch_monitor_name(mgr, port, name, sizeof(name));
-			seq_printf(m, "%10d%10d%10d%10d%20s\n",
-				   i,
-				   port->port_num,
-				   port->vcpi.vcpi,
-				   port->vcpi.num_slots,
-				   (*name != 0) ? name : "Unknown");
-		} else
-			seq_printf(m, "%6d - Unused\n", i);
-	}
-	seq_printf(m, "\n*** Payload Info ***\n");
-	seq_printf(m, "|   idx   |  state  |  start slot  | # slots |\n");
-	for (i = 0; i < mgr->max_payloads; i++) {
-		seq_printf(m, "%10d%10d%15d%10d\n",
-			   i,
-			   mgr->payloads[i].payload_state,
-			   mgr->payloads[i].start_slot,
-			   mgr->payloads[i].num_slots);
-	}
-	mutex_unlock(&mgr->payload_lock);
-
-	seq_printf(m, "\n*** DPCD Info ***\n");
-	mutex_lock(&mgr->lock);
-	if (mgr->mst_primary) {
-		u8 buf[DP_PAYLOAD_TABLE_SIZE];
-		int ret;
-
-		ret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, buf, DP_RECEIVER_CAP_SIZE);
-		if (ret) {
-			seq_printf(m, "dpcd read failed\n");
-			goto out;
-		}
-		seq_printf(m, "dpcd: %*ph\n", DP_RECEIVER_CAP_SIZE, buf);
-
-		ret = drm_dp_dpcd_read(mgr->aux, DP_FAUX_CAP, buf, 2);
-		if (ret) {
-			seq_printf(m, "faux/mst read failed\n");
-			goto out;
-		}
-		seq_printf(m, "faux/mst: %*ph\n", 2, buf);
-
-		ret = drm_dp_dpcd_read(mgr->aux, DP_MSTM_CTRL, buf, 1);
-		if (ret) {
-			seq_printf(m, "mst ctrl read failed\n");
-			goto out;
-		}
-		seq_printf(m, "mst ctrl: %*ph\n", 1, buf);
-
-		/* dump the standard OUI branch header */
-		ret = drm_dp_dpcd_read(mgr->aux, DP_BRANCH_OUI, buf, DP_BRANCH_OUI_HEADER_SIZE);
-		if (ret) {
-			seq_printf(m, "branch oui read failed\n");
-			goto out;
-		}
-		seq_printf(m, "branch oui: %*phN devid: ", 3, buf);
-
-		for (i = 0x3; i < 0x8 && buf[i]; i++)
-			seq_printf(m, "%c", buf[i]);
-		seq_printf(m, " revision: hw: %x.%x sw: %x.%x\n",
-			   buf[0x9] >> 4, buf[0x9] & 0xf, buf[0xa], buf[0xb]);
-		if (dump_dp_payload_table(mgr, buf))
-			seq_printf(m, "payload table: %*ph\n", DP_PAYLOAD_TABLE_SIZE, buf);
-	}
-
-out:
-	mutex_unlock(&mgr->lock);
-
-}
-EXPORT_SYMBOL(drm_dp_mst_dump_topology);
-
-static void drm_dp_tx_work(struct work_struct *work)
-{
-	struct drm_dp_mst_topology_mgr *mgr = container_of(work, struct drm_dp_mst_topology_mgr, tx_work);
-
-	mutex_lock(&mgr->qlock);
-	if (!list_empty(&mgr->tx_msg_downq))
-		process_single_down_tx_qlock(mgr);
-	mutex_unlock(&mgr->qlock);
-}
-
-static inline void
-drm_dp_delayed_destroy_port(struct drm_dp_mst_port *port)
-{
-	drm_dp_port_set_pdt(port, DP_PEER_DEVICE_NONE, port->mcs);
-
-	if (port->connector) {
-		drm_connector_unregister(port->connector);
-		drm_connector_put(port->connector);
-	}
-
-	drm_dp_mst_put_port_malloc(port);
-}
-
-static inline void
-drm_dp_delayed_destroy_mstb(struct drm_dp_mst_branch *mstb)
-{
-	struct drm_dp_mst_topology_mgr *mgr = mstb->mgr;
-	struct drm_dp_mst_port *port, *port_tmp;
-	struct drm_dp_sideband_msg_tx *txmsg, *txmsg_tmp;
-	bool wake_tx = false;
-
-	mutex_lock(&mgr->lock);
-	list_for_each_entry_safe(port, port_tmp, &mstb->ports, next) {
-		list_del(&port->next);
-		drm_dp_mst_topology_put_port(port);
-	}
-	mutex_unlock(&mgr->lock);
-
-	/* drop any tx slot msg */
-	mutex_lock(&mstb->mgr->qlock);
-	list_for_each_entry_safe(txmsg, txmsg_tmp, &mgr->tx_msg_downq, next) {
-		if (txmsg->dst != mstb)
-			continue;
-
-		txmsg->state = DRM_DP_SIDEBAND_TX_TIMEOUT;
-		list_del(&txmsg->next);
-		wake_tx = true;
-	}
-	mutex_unlock(&mstb->mgr->qlock);
-
-	if (wake_tx)
-		wake_up_all(&mstb->mgr->tx_waitq);
-
-	drm_dp_mst_put_mstb_malloc(mstb);
-}
-
-static void drm_dp_delayed_destroy_work(struct work_struct *work)
-{
-	struct drm_dp_mst_topology_mgr *mgr =
-		container_of(work, struct drm_dp_mst_topology_mgr,
-			     delayed_destroy_work);
-	bool send_hotplug = false, go_again;
-
-	/*
-	 * Not a regular list traverse as we have to drop the destroy
-	 * connector lock before destroying the mstb/port, to avoid AB->BA
-	 * ordering between this lock and the config mutex.
-	 */
-	do {
-		go_again = false;
-
-		for (;;) {
-			struct drm_dp_mst_branch *mstb;
-
-			mutex_lock(&mgr->delayed_destroy_lock);
-			mstb = list_first_entry_or_null(&mgr->destroy_branch_device_list,
-							struct drm_dp_mst_branch,
-							destroy_next);
-			if (mstb)
-				list_del(&mstb->destroy_next);
-			mutex_unlock(&mgr->delayed_destroy_lock);
-
-			if (!mstb)
-				break;
-
-			drm_dp_delayed_destroy_mstb(mstb);
-			go_again = true;
-		}
-
-		for (;;) {
-			struct drm_dp_mst_port *port;
-
-			mutex_lock(&mgr->delayed_destroy_lock);
-			port = list_first_entry_or_null(&mgr->destroy_port_list,
-							struct drm_dp_mst_port,
-							next);
-			if (port)
-				list_del(&port->next);
-			mutex_unlock(&mgr->delayed_destroy_lock);
-
-			if (!port)
-				break;
-
-			drm_dp_delayed_destroy_port(port);
-			send_hotplug = true;
-			go_again = true;
-		}
-	} while (go_again);
-
-	if (send_hotplug)
-		drm_kms_helper_hotplug_event(mgr->dev);
-}
-
-static struct drm_private_state *
-drm_dp_mst_duplicate_state(struct drm_private_obj *obj)
-{
-	struct drm_dp_mst_topology_state *state, *old_state =
-		to_dp_mst_topology_state(obj->state);
-	struct drm_dp_vcpi_allocation *pos, *vcpi;
-
-	state = kmemdup(old_state, sizeof(*state), GFP_KERNEL);
-	if (!state)
-		return NULL;
-
-	__drm_atomic_helper_private_obj_duplicate_state(obj, &state->base);
-
-	INIT_LIST_HEAD(&state->vcpis);
-
-	list_for_each_entry(pos, &old_state->vcpis, next) {
-		/* Prune leftover freed VCPI allocations */
-		if (!pos->vcpi)
-			continue;
-
-		vcpi = kmemdup(pos, sizeof(*vcpi), GFP_KERNEL);
-		if (!vcpi)
-			goto fail;
-
-		drm_dp_mst_get_port_malloc(vcpi->port);
-		list_add(&vcpi->next, &state->vcpis);
-	}
-
-	return &state->base;
-
-fail:
-	list_for_each_entry_safe(pos, vcpi, &state->vcpis, next) {
-		drm_dp_mst_put_port_malloc(pos->port);
-		kfree(pos);
-	}
-	kfree(state);
-
-	return NULL;
-}
-
-static void drm_dp_mst_destroy_state(struct drm_private_obj *obj,
-				     struct drm_private_state *state)
-{
-	struct drm_dp_mst_topology_state *mst_state =
-		to_dp_mst_topology_state(state);
-	struct drm_dp_vcpi_allocation *pos, *tmp;
-
-	list_for_each_entry_safe(pos, tmp, &mst_state->vcpis, next) {
-		/* We only keep references to ports with non-zero VCPIs */
-		if (pos->vcpi)
-			drm_dp_mst_put_port_malloc(pos->port);
-		kfree(pos);
-	}
-
-	kfree(mst_state);
-}
-
-static bool drm_dp_mst_port_downstream_of_branch(struct drm_dp_mst_port *port,
-						 struct drm_dp_mst_branch *branch)
-{
-	while (port->parent) {
-		if (port->parent == branch)
-			return true;
-
-		if (port->parent->port_parent)
-			port = port->parent->port_parent;
-		else
-			break;
-	}
-	return false;
-}
-
-static int
-drm_dp_mst_atomic_check_port_bw_limit(struct drm_dp_mst_port *port,
-				      struct drm_dp_mst_topology_state *state);
-
-static int
-drm_dp_mst_atomic_check_mstb_bw_limit(struct drm_dp_mst_branch *mstb,
-				      struct drm_dp_mst_topology_state *state)
-{
-	struct drm_dp_vcpi_allocation *vcpi;
-	struct drm_dp_mst_port *port;
-	int pbn_used = 0, ret;
-	bool found = false;
-
-	/* Check that we have at least one port in our state that's downstream
-	 * of this branch, otherwise we can skip this branch
-	 */
-	list_for_each_entry(vcpi, &state->vcpis, next) {
-		if (!vcpi->pbn ||
-		    !drm_dp_mst_port_downstream_of_branch(vcpi->port, mstb))
-			continue;
-
-		found = true;
-		break;
-	}
-	if (!found)
-		return 0;
-
-	if (mstb->port_parent)
-		drm_dbg_atomic(mstb->mgr->dev,
-			       "[MSTB:%p] [MST PORT:%p] Checking bandwidth limits on [MSTB:%p]\n",
-			       mstb->port_parent->parent, mstb->port_parent, mstb);
-	else
-		drm_dbg_atomic(mstb->mgr->dev, "[MSTB:%p] Checking bandwidth limits\n", mstb);
-
-	list_for_each_entry(port, &mstb->ports, next) {
-		ret = drm_dp_mst_atomic_check_port_bw_limit(port, state);
-		if (ret < 0)
-			return ret;
-
-		pbn_used += ret;
-	}
-
-	return pbn_used;
-}
-
-static int
-drm_dp_mst_atomic_check_port_bw_limit(struct drm_dp_mst_port *port,
-				      struct drm_dp_mst_topology_state *state)
-{
-	struct drm_dp_vcpi_allocation *vcpi;
-	int pbn_used = 0;
-
-	if (port->pdt == DP_PEER_DEVICE_NONE)
-		return 0;
-
-	if (drm_dp_mst_is_end_device(port->pdt, port->mcs)) {
-		bool found = false;
-
-		list_for_each_entry(vcpi, &state->vcpis, next) {
-			if (vcpi->port != port)
-				continue;
-			if (!vcpi->pbn)
-				return 0;
-
-			found = true;
-			break;
-		}
-		if (!found)
-			return 0;
-
-		/*
-		 * This could happen if the sink deasserted its HPD line, but
-		 * the branch device still reports it as attached (PDT != NONE).
-		 */
-		if (!port->full_pbn) {
-			drm_dbg_atomic(port->mgr->dev,
-				       "[MSTB:%p] [MST PORT:%p] no BW available for the port\n",
-				       port->parent, port);
-			return -EINVAL;
-		}
-
-		pbn_used = vcpi->pbn;
-	} else {
-		pbn_used = drm_dp_mst_atomic_check_mstb_bw_limit(port->mstb,
-								 state);
-		if (pbn_used <= 0)
-			return pbn_used;
-	}
-
-	if (pbn_used > port->full_pbn) {
-		drm_dbg_atomic(port->mgr->dev,
-			       "[MSTB:%p] [MST PORT:%p] required PBN of %d exceeds port limit of %d\n",
-			       port->parent, port, pbn_used, port->full_pbn);
-		return -ENOSPC;
-	}
-
-	drm_dbg_atomic(port->mgr->dev, "[MSTB:%p] [MST PORT:%p] uses %d out of %d PBN\n",
-		       port->parent, port, pbn_used, port->full_pbn);
-
-	return pbn_used;
-}
-
-static inline int
-drm_dp_mst_atomic_check_vcpi_alloc_limit(struct drm_dp_mst_topology_mgr *mgr,
-					 struct drm_dp_mst_topology_state *mst_state)
-{
-	struct drm_dp_vcpi_allocation *vcpi;
-	int avail_slots = mst_state->total_avail_slots, payload_count = 0;
-
-	list_for_each_entry(vcpi, &mst_state->vcpis, next) {
-		/* Releasing VCPI is always OK-even if the port is gone */
-		if (!vcpi->vcpi) {
-			drm_dbg_atomic(mgr->dev, "[MST PORT:%p] releases all VCPI slots\n",
-				       vcpi->port);
-			continue;
-		}
-
-		drm_dbg_atomic(mgr->dev, "[MST PORT:%p] requires %d vcpi slots\n",
-			       vcpi->port, vcpi->vcpi);
-
-		avail_slots -= vcpi->vcpi;
-		if (avail_slots < 0) {
-			drm_dbg_atomic(mgr->dev,
-				       "[MST PORT:%p] not enough VCPI slots in mst state %p (avail=%d)\n",
-				       vcpi->port, mst_state, avail_slots + vcpi->vcpi);
-			return -ENOSPC;
-		}
-
-		if (++payload_count > mgr->max_payloads) {
-			drm_dbg_atomic(mgr->dev,
-				       "[MST MGR:%p] state %p has too many payloads (max=%d)\n",
-				       mgr, mst_state, mgr->max_payloads);
-			return -EINVAL;
-		}
-	}
-	drm_dbg_atomic(mgr->dev, "[MST MGR:%p] mst state %p VCPI avail=%d used=%d\n",
-		       mgr, mst_state, avail_slots, mst_state->total_avail_slots - avail_slots);
-
-	return 0;
-}
-
-/**
- * drm_dp_mst_add_affected_dsc_crtcs
- * @state: Pointer to the new struct drm_dp_mst_topology_state
- * @mgr: MST topology manager
- *
- * Whenever there is a change in mst topology
- * DSC configuration would have to be recalculated
- * therefore we need to trigger modeset on all affected
- * CRTCs in that topology
- *
- * See also:
- * drm_dp_mst_atomic_enable_dsc()
- */
-int drm_dp_mst_add_affected_dsc_crtcs(struct drm_atomic_state *state, struct drm_dp_mst_topology_mgr *mgr)
-{
-	struct drm_dp_mst_topology_state *mst_state;
-	struct drm_dp_vcpi_allocation *pos;
-	struct drm_connector *connector;
-	struct drm_connector_state *conn_state;
-	struct drm_crtc *crtc;
-	struct drm_crtc_state *crtc_state;
-
-	mst_state = drm_atomic_get_mst_topology_state(state, mgr);
-
-	if (IS_ERR(mst_state))
-		return -EINVAL;
-
-	list_for_each_entry(pos, &mst_state->vcpis, next) {
-
-		connector = pos->port->connector;
-
-		if (!connector)
-			return -EINVAL;
-
-		conn_state = drm_atomic_get_connector_state(state, connector);
-
-		if (IS_ERR(conn_state))
-			return PTR_ERR(conn_state);
-
-		crtc = conn_state->crtc;
-
-		if (!crtc)
-			continue;
-
-		if (!drm_dp_mst_dsc_aux_for_port(pos->port))
-			continue;
-
-		crtc_state = drm_atomic_get_crtc_state(mst_state->base.state, crtc);
-
-		if (IS_ERR(crtc_state))
-			return PTR_ERR(crtc_state);
-
-		drm_dbg_atomic(mgr->dev, "[MST MGR:%p] Setting mode_changed flag on CRTC %p\n",
-			       mgr, crtc);
-
-		crtc_state->mode_changed = true;
-	}
-	return 0;
-}
-EXPORT_SYMBOL(drm_dp_mst_add_affected_dsc_crtcs);
-
-/**
- * drm_dp_mst_atomic_enable_dsc - Set DSC Enable Flag to On/Off
- * @state: Pointer to the new drm_atomic_state
- * @port: Pointer to the affected MST Port
- * @pbn: Newly recalculated bw required for link with DSC enabled
- * @pbn_div: Divider to calculate correct number of pbn per slot
- * @enable: Boolean flag to enable or disable DSC on the port
- *
- * This function enables DSC on the given Port
- * by recalculating its vcpi from pbn provided
- * and sets dsc_enable flag to keep track of which
- * ports have DSC enabled
- *
- */
-int drm_dp_mst_atomic_enable_dsc(struct drm_atomic_state *state,
-				 struct drm_dp_mst_port *port,
-				 int pbn, int pbn_div,
-				 bool enable)
-{
-	struct drm_dp_mst_topology_state *mst_state;
-	struct drm_dp_vcpi_allocation *pos;
-	bool found = false;
-	int vcpi = 0;
-
-	mst_state = drm_atomic_get_mst_topology_state(state, port->mgr);
-
-	if (IS_ERR(mst_state))
-		return PTR_ERR(mst_state);
-
-	list_for_each_entry(pos, &mst_state->vcpis, next) {
-		if (pos->port == port) {
-			found = true;
-			break;
-		}
-	}
-
-	if (!found) {
-		drm_dbg_atomic(state->dev,
-			       "[MST PORT:%p] Couldn't find VCPI allocation in mst state %p\n",
-			       port, mst_state);
-		return -EINVAL;
-	}
-
-	if (pos->dsc_enabled == enable) {
-		drm_dbg_atomic(state->dev,
-			       "[MST PORT:%p] DSC flag is already set to %d, returning %d VCPI slots\n",
-			       port, enable, pos->vcpi);
-		vcpi = pos->vcpi;
-	}
-
-	if (enable) {
-		vcpi = drm_dp_atomic_find_vcpi_slots(state, port->mgr, port, pbn, pbn_div);
-		drm_dbg_atomic(state->dev,
-			       "[MST PORT:%p] Enabling DSC flag, reallocating %d VCPI slots on the port\n",
-			       port, vcpi);
-		if (vcpi < 0)
-			return -EINVAL;
-	}
-
-	pos->dsc_enabled = enable;
-
-	return vcpi;
-}
-EXPORT_SYMBOL(drm_dp_mst_atomic_enable_dsc);
-/**
- * drm_dp_mst_atomic_check - Check that the new state of an MST topology in an
- * atomic update is valid
- * @state: Pointer to the new &struct drm_dp_mst_topology_state
- *
- * Checks the given topology state for an atomic update to ensure that it's
- * valid. This includes checking whether there's enough bandwidth to support
- * the new VCPI allocations in the atomic update.
- *
- * Any atomic drivers supporting DP MST must make sure to call this after
- * checking the rest of their state in their
- * &drm_mode_config_funcs.atomic_check() callback.
- *
- * See also:
- * drm_dp_atomic_find_vcpi_slots()
- * drm_dp_atomic_release_vcpi_slots()
- *
- * Returns:
- *
- * 0 if the new state is valid, negative error code otherwise.
- */
-int drm_dp_mst_atomic_check(struct drm_atomic_state *state)
-{
-	struct drm_dp_mst_topology_mgr *mgr;
-	struct drm_dp_mst_topology_state *mst_state;
-	int i, ret = 0;
-
-	for_each_new_mst_mgr_in_state(state, mgr, mst_state, i) {
-		if (!mgr->mst_state)
-			continue;
-
-		ret = drm_dp_mst_atomic_check_vcpi_alloc_limit(mgr, mst_state);
-		if (ret)
-			break;
-
-		mutex_lock(&mgr->lock);
-		ret = drm_dp_mst_atomic_check_mstb_bw_limit(mgr->mst_primary,
-							    mst_state);
-		mutex_unlock(&mgr->lock);
-		if (ret < 0)
-			break;
-		else
-			ret = 0;
-	}
-
-	return ret;
-}
-EXPORT_SYMBOL(drm_dp_mst_atomic_check);
-
-const struct drm_private_state_funcs drm_dp_mst_topology_state_funcs = {
-	.atomic_duplicate_state = drm_dp_mst_duplicate_state,
-	.atomic_destroy_state = drm_dp_mst_destroy_state,
-};
-EXPORT_SYMBOL(drm_dp_mst_topology_state_funcs);
-
-/**
- * drm_atomic_get_mst_topology_state: get MST topology state
- *
- * @state: global atomic state
- * @mgr: MST topology manager, also the private object in this case
- *
- * This function wraps drm_atomic_get_priv_obj_state() passing in the MST atomic
- * state vtable so that the private object state returned is that of a MST
- * topology object. Also, drm_atomic_get_private_obj_state() expects the caller
- * to care of the locking, so warn if don't hold the connection_mutex.
- *
- * RETURNS:
- *
- * The MST topology state or error pointer.
- */
-struct drm_dp_mst_topology_state *drm_atomic_get_mst_topology_state(struct drm_atomic_state *state,
-								    struct drm_dp_mst_topology_mgr *mgr)
-{
-	return to_dp_mst_topology_state(drm_atomic_get_private_obj_state(state, &mgr->base));
-}
-EXPORT_SYMBOL(drm_atomic_get_mst_topology_state);
-
-/**
- * drm_dp_mst_topology_mgr_init - initialise a topology manager
- * @mgr: manager struct to initialise
- * @dev: device providing this structure - for i2c addition.
- * @aux: DP helper aux channel to talk to this device
- * @max_dpcd_transaction_bytes: hw specific DPCD transaction limit
- * @max_payloads: maximum number of payloads this GPU can source
- * @max_lane_count: maximum number of lanes this GPU supports
- * @max_link_rate: maximum link rate per lane this GPU supports in kHz
- * @conn_base_id: the connector object ID the MST device is connected to.
- *
- * Return 0 for success, or negative error code on failure
- */
-int drm_dp_mst_topology_mgr_init(struct drm_dp_mst_topology_mgr *mgr,
-				 struct drm_device *dev, struct drm_dp_aux *aux,
-				 int max_dpcd_transaction_bytes, int max_payloads,
-				 int max_lane_count, int max_link_rate,
-				 int conn_base_id)
-{
-	struct drm_dp_mst_topology_state *mst_state;
-
-	mutex_init(&mgr->lock);
-	mutex_init(&mgr->qlock);
-	mutex_init(&mgr->payload_lock);
-	mutex_init(&mgr->delayed_destroy_lock);
-	mutex_init(&mgr->up_req_lock);
-	mutex_init(&mgr->probe_lock);
-#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
-	mutex_init(&mgr->topology_ref_history_lock);
-#endif
-	INIT_LIST_HEAD(&mgr->tx_msg_downq);
-	INIT_LIST_HEAD(&mgr->destroy_port_list);
-	INIT_LIST_HEAD(&mgr->destroy_branch_device_list);
-	INIT_LIST_HEAD(&mgr->up_req_list);
-
-	/*
-	 * delayed_destroy_work will be queued on a dedicated WQ, so that any
-	 * requeuing will be also flushed when deiniting the topology manager.
-	 */
-	mgr->delayed_destroy_wq = alloc_ordered_workqueue("drm_dp_mst_wq", 0);
-	if (mgr->delayed_destroy_wq == NULL)
-		return -ENOMEM;
-
-	INIT_WORK(&mgr->work, drm_dp_mst_link_probe_work);
-	INIT_WORK(&mgr->tx_work, drm_dp_tx_work);
-	INIT_WORK(&mgr->delayed_destroy_work, drm_dp_delayed_destroy_work);
-	INIT_WORK(&mgr->up_req_work, drm_dp_mst_up_req_work);
-	init_waitqueue_head(&mgr->tx_waitq);
-	mgr->dev = dev;
-	mgr->aux = aux;
-	mgr->max_dpcd_transaction_bytes = max_dpcd_transaction_bytes;
-	mgr->max_payloads = max_payloads;
-	mgr->max_lane_count = max_lane_count;
-	mgr->max_link_rate = max_link_rate;
-	mgr->conn_base_id = conn_base_id;
-	if (max_payloads + 1 > sizeof(mgr->payload_mask) * 8 ||
-	    max_payloads + 1 > sizeof(mgr->vcpi_mask) * 8)
-		return -EINVAL;
-	mgr->payloads = kcalloc(max_payloads, sizeof(struct drm_dp_payload), GFP_KERNEL);
-	if (!mgr->payloads)
-		return -ENOMEM;
-	mgr->proposed_vcpis = kcalloc(max_payloads, sizeof(struct drm_dp_vcpi *), GFP_KERNEL);
-	if (!mgr->proposed_vcpis)
-		return -ENOMEM;
-	set_bit(0, &mgr->payload_mask);
-
-	mst_state = kzalloc(sizeof(*mst_state), GFP_KERNEL);
-	if (mst_state == NULL)
-		return -ENOMEM;
-
-	mst_state->total_avail_slots = 63;
-	mst_state->start_slot = 1;
-
-	mst_state->mgr = mgr;
-	INIT_LIST_HEAD(&mst_state->vcpis);
-
-	drm_atomic_private_obj_init(dev, &mgr->base,
-				    &mst_state->base,
-				    &drm_dp_mst_topology_state_funcs);
-
-	return 0;
-}
-EXPORT_SYMBOL(drm_dp_mst_topology_mgr_init);
-
-/**
- * drm_dp_mst_topology_mgr_destroy() - destroy topology manager.
- * @mgr: manager to destroy
- */
-void drm_dp_mst_topology_mgr_destroy(struct drm_dp_mst_topology_mgr *mgr)
-{
-	drm_dp_mst_topology_mgr_set_mst(mgr, false);
-	flush_work(&mgr->work);
-	/* The following will also drain any requeued work on the WQ. */
-	if (mgr->delayed_destroy_wq) {
-		destroy_workqueue(mgr->delayed_destroy_wq);
-		mgr->delayed_destroy_wq = NULL;
-	}
-	mutex_lock(&mgr->payload_lock);
-	kfree(mgr->payloads);
-	mgr->payloads = NULL;
-	kfree(mgr->proposed_vcpis);
-	mgr->proposed_vcpis = NULL;
-	mutex_unlock(&mgr->payload_lock);
-	mgr->dev = NULL;
-	mgr->aux = NULL;
-	drm_atomic_private_obj_fini(&mgr->base);
-	mgr->funcs = NULL;
-
-	mutex_destroy(&mgr->delayed_destroy_lock);
-	mutex_destroy(&mgr->payload_lock);
-	mutex_destroy(&mgr->qlock);
-	mutex_destroy(&mgr->lock);
-	mutex_destroy(&mgr->up_req_lock);
-	mutex_destroy(&mgr->probe_lock);
-#if IS_ENABLED(CONFIG_DRM_DEBUG_DP_MST_TOPOLOGY_REFS)
-	mutex_destroy(&mgr->topology_ref_history_lock);
-#endif
-}
-EXPORT_SYMBOL(drm_dp_mst_topology_mgr_destroy);
-
-static bool remote_i2c_read_ok(const struct i2c_msg msgs[], int num)
-{
-	int i;
-
-	if (num - 1 > DP_REMOTE_I2C_READ_MAX_TRANSACTIONS)
-		return false;
-
-	for (i = 0; i < num - 1; i++) {
-		if (msgs[i].flags & I2C_M_RD ||
-		    msgs[i].len > 0xff)
-			return false;
-	}
-
-	return msgs[num - 1].flags & I2C_M_RD &&
-		msgs[num - 1].len <= 0xff;
-}
-
-static bool remote_i2c_write_ok(const struct i2c_msg msgs[], int num)
-{
-	int i;
-
-	for (i = 0; i < num - 1; i++) {
-		if (msgs[i].flags & I2C_M_RD || !(msgs[i].flags & I2C_M_STOP) ||
-		    msgs[i].len > 0xff)
-			return false;
-	}
-
-	return !(msgs[num - 1].flags & I2C_M_RD) && msgs[num - 1].len <= 0xff;
-}
-
-static int drm_dp_mst_i2c_read(struct drm_dp_mst_branch *mstb,
-			       struct drm_dp_mst_port *port,
-			       struct i2c_msg *msgs, int num)
-{
-	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
-	unsigned int i;
-	struct drm_dp_sideband_msg_req_body msg;
-	struct drm_dp_sideband_msg_tx *txmsg = NULL;
-	int ret;
-
-	memset(&msg, 0, sizeof(msg));
-	msg.req_type = DP_REMOTE_I2C_READ;
-	msg.u.i2c_read.num_transactions = num - 1;
-	msg.u.i2c_read.port_number = port->port_num;
-	for (i = 0; i < num - 1; i++) {
-		msg.u.i2c_read.transactions[i].i2c_dev_id = msgs[i].addr;
-		msg.u.i2c_read.transactions[i].num_bytes = msgs[i].len;
-		msg.u.i2c_read.transactions[i].bytes = msgs[i].buf;
-		msg.u.i2c_read.transactions[i].no_stop_bit = !(msgs[i].flags & I2C_M_STOP);
-	}
-	msg.u.i2c_read.read_i2c_device_id = msgs[num - 1].addr;
-	msg.u.i2c_read.num_bytes_read = msgs[num - 1].len;
-
-	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
-	if (!txmsg) {
-		ret = -ENOMEM;
-		goto out;
-	}
-
-	txmsg->dst = mstb;
-	drm_dp_encode_sideband_req(&msg, txmsg);
-
-	drm_dp_queue_down_tx(mgr, txmsg);
-
-	ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
-	if (ret > 0) {
-
-		if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
-			ret = -EREMOTEIO;
-			goto out;
-		}
-		if (txmsg->reply.u.remote_i2c_read_ack.num_bytes != msgs[num - 1].len) {
-			ret = -EIO;
-			goto out;
-		}
-		memcpy(msgs[num - 1].buf, txmsg->reply.u.remote_i2c_read_ack.bytes, msgs[num - 1].len);
-		ret = num;
-	}
-out:
-	kfree(txmsg);
-	return ret;
-}
-
-static int drm_dp_mst_i2c_write(struct drm_dp_mst_branch *mstb,
-				struct drm_dp_mst_port *port,
-				struct i2c_msg *msgs, int num)
-{
-	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
-	unsigned int i;
-	struct drm_dp_sideband_msg_req_body msg;
-	struct drm_dp_sideband_msg_tx *txmsg = NULL;
-	int ret;
-
-	txmsg = kzalloc(sizeof(*txmsg), GFP_KERNEL);
-	if (!txmsg) {
-		ret = -ENOMEM;
-		goto out;
-	}
-	for (i = 0; i < num; i++) {
-		memset(&msg, 0, sizeof(msg));
-		msg.req_type = DP_REMOTE_I2C_WRITE;
-		msg.u.i2c_write.port_number = port->port_num;
-		msg.u.i2c_write.write_i2c_device_id = msgs[i].addr;
-		msg.u.i2c_write.num_bytes = msgs[i].len;
-		msg.u.i2c_write.bytes = msgs[i].buf;
-
-		memset(txmsg, 0, sizeof(*txmsg));
-		txmsg->dst = mstb;
-
-		drm_dp_encode_sideband_req(&msg, txmsg);
-		drm_dp_queue_down_tx(mgr, txmsg);
-
-		ret = drm_dp_mst_wait_tx_reply(mstb, txmsg);
-		if (ret > 0) {
-			if (txmsg->reply.reply_type == DP_SIDEBAND_REPLY_NAK) {
-				ret = -EREMOTEIO;
-				goto out;
-			}
-		} else {
-			goto out;
-		}
-	}
-	ret = num;
-out:
-	kfree(txmsg);
-	return ret;
-}
-
-/* I2C device */
-static int drm_dp_mst_i2c_xfer(struct i2c_adapter *adapter,
-			       struct i2c_msg *msgs, int num)
-{
-	struct drm_dp_aux *aux = adapter->algo_data;
-	struct drm_dp_mst_port *port =
-		container_of(aux, struct drm_dp_mst_port, aux);
-	struct drm_dp_mst_branch *mstb;
-	struct drm_dp_mst_topology_mgr *mgr = port->mgr;
-	int ret;
-
-	mstb = drm_dp_mst_topology_get_mstb_validated(mgr, port->parent);
-	if (!mstb)
-		return -EREMOTEIO;
-
-	if (remote_i2c_read_ok(msgs, num)) {
-		ret = drm_dp_mst_i2c_read(mstb, port, msgs, num);
-	} else if (remote_i2c_write_ok(msgs, num)) {
-		ret = drm_dp_mst_i2c_write(mstb, port, msgs, num);
-	} else {
-		drm_dbg_kms(mgr->dev, "Unsupported I2C transaction for MST device\n");
-		ret = -EIO;
-	}
-
-	drm_dp_mst_topology_put_mstb(mstb);
-	return ret;
-}
-
-static u32 drm_dp_mst_i2c_functionality(struct i2c_adapter *adapter)
-{
-	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
-	       I2C_FUNC_SMBUS_READ_BLOCK_DATA |
-	       I2C_FUNC_SMBUS_BLOCK_PROC_CALL |
-	       I2C_FUNC_10BIT_ADDR;
-}
-
-static const struct i2c_algorithm drm_dp_mst_i2c_algo = {
-	.functionality = drm_dp_mst_i2c_functionality,
-	.master_xfer = drm_dp_mst_i2c_xfer,
-};
-
-/**
- * drm_dp_mst_register_i2c_bus() - register an I2C adapter for I2C-over-AUX
- * @port: The port to add the I2C bus on
- *
- * Returns 0 on success or a negative error code on failure.
- */
-static int drm_dp_mst_register_i2c_bus(struct drm_dp_mst_port *port)
-{
-	struct drm_dp_aux *aux = &port->aux;
-	struct device *parent_dev = port->mgr->dev->dev;
-
-	aux->ddc.algo = &drm_dp_mst_i2c_algo;
-	aux->ddc.algo_data = aux;
-	aux->ddc.retries = 3;
-
-	aux->ddc.class = I2C_CLASS_DDC;
-	aux->ddc.owner = THIS_MODULE;
-	/* FIXME: set the kdev of the port's connector as parent */
-	aux->ddc.dev.parent = parent_dev;
-	aux->ddc.dev.of_node = parent_dev->of_node;
-
-	strlcpy(aux->ddc.name, aux->name ? aux->name : dev_name(parent_dev),
-		sizeof(aux->ddc.name));
-
-	return i2c_add_adapter(&aux->ddc);
-}
-
-/**
- * drm_dp_mst_unregister_i2c_bus() - unregister an I2C-over-AUX adapter
- * @port: The port to remove the I2C bus from
- */
-static void drm_dp_mst_unregister_i2c_bus(struct drm_dp_mst_port *port)
-{
-	i2c_del_adapter(&port->aux.ddc);
-}
-
-/**
- * drm_dp_mst_is_virtual_dpcd() - Is the given port a virtual DP Peer Device
- * @port: The port to check
- *
- * A single physical MST hub object can be represented in the topology
- * by multiple branches, with virtual ports between those branches.
- *
- * As of DP1.4, An MST hub with internal (virtual) ports must expose
- * certain DPCD registers over those ports. See sections 2.6.1.1.1
- * and 2.6.1.1.2 of Display Port specification v1.4 for details.
- *
- * May acquire mgr->lock
- *
- * Returns:
- * true if the port is a virtual DP peer device, false otherwise
- */
-static bool drm_dp_mst_is_virtual_dpcd(struct drm_dp_mst_port *port)
-{
-	struct drm_dp_mst_port *downstream_port;
-
-	if (!port || port->dpcd_rev < DP_DPCD_REV_14)
-		return false;
-
-	/* Virtual DP Sink (Internal Display Panel) */
-	if (port->port_num >= 8)
-		return true;
-
-	/* DP-to-HDMI Protocol Converter */
-	if (port->pdt == DP_PEER_DEVICE_DP_LEGACY_CONV &&
-	    !port->mcs &&
-	    port->ldps)
-		return true;
-
-	/* DP-to-DP */
-	mutex_lock(&port->mgr->lock);
-	if (port->pdt == DP_PEER_DEVICE_MST_BRANCHING &&
-	    port->mstb &&
-	    port->mstb->num_ports == 2) {
-		list_for_each_entry(downstream_port, &port->mstb->ports, next) {
-			if (downstream_port->pdt == DP_PEER_DEVICE_SST_SINK &&
-			    !downstream_port->input) {
-				mutex_unlock(&port->mgr->lock);
-				return true;
-			}
-		}
-	}
-	mutex_unlock(&port->mgr->lock);
-
-	return false;
-}
-
-/**
- * drm_dp_mst_dsc_aux_for_port() - Find the correct aux for DSC
- * @port: The port to check. A leaf of the MST tree with an attached display.
- *
- * Depending on the situation, DSC may be enabled via the endpoint aux,
- * the immediately upstream aux, or the connector's physical aux.
- *
- * This is both the correct aux to read DSC_CAPABILITY and the
- * correct aux to write DSC_ENABLED.
- *
- * This operation can be expensive (up to four aux reads), so
- * the caller should cache the return.
- *
- * Returns:
- * NULL if DSC cannot be enabled on this port, otherwise the aux device
- */
-struct drm_dp_aux *drm_dp_mst_dsc_aux_for_port(struct drm_dp_mst_port *port)
-{
-	struct drm_dp_mst_port *immediate_upstream_port;
-	struct drm_dp_mst_port *fec_port;
-	struct drm_dp_desc desc = {};
-	u8 endpoint_fec;
-	u8 endpoint_dsc;
-
-	if (!port)
-		return NULL;
-
-	if (port->parent->port_parent)
-		immediate_upstream_port = port->parent->port_parent;
-	else
-		immediate_upstream_port = NULL;
-
-	fec_port = immediate_upstream_port;
-	while (fec_port) {
-		/*
-		 * Each physical link (i.e. not a virtual port) between the
-		 * output and the primary device must support FEC
-		 */
-		if (!drm_dp_mst_is_virtual_dpcd(fec_port) &&
-		    !fec_port->fec_capable)
-			return NULL;
-
-		fec_port = fec_port->parent->port_parent;
-	}
-
-	/* DP-to-DP peer device */
-	if (drm_dp_mst_is_virtual_dpcd(immediate_upstream_port)) {
-		u8 upstream_dsc;
-
-		if (drm_dp_dpcd_read(&port->aux,
-				     DP_DSC_SUPPORT, &endpoint_dsc, 1) != 1)
-			return NULL;
-		if (drm_dp_dpcd_read(&port->aux,
-				     DP_FEC_CAPABILITY, &endpoint_fec, 1) != 1)
-			return NULL;
-		if (drm_dp_dpcd_read(&immediate_upstream_port->aux,
-				     DP_DSC_SUPPORT, &upstream_dsc, 1) != 1)
-			return NULL;
-
-		/* Enpoint decompression with DP-to-DP peer device */
-		if ((endpoint_dsc & DP_DSC_DECOMPRESSION_IS_SUPPORTED) &&
-		    (endpoint_fec & DP_FEC_CAPABLE) &&
-		    (upstream_dsc & 0x2) /* DSC passthrough */)
-			return &port->aux;
-
-		/* Virtual DPCD decompression with DP-to-DP peer device */
-		return &immediate_upstream_port->aux;
-	}
-
-	/* Virtual DPCD decompression with DP-to-HDMI or Virtual DP Sink */
-	if (drm_dp_mst_is_virtual_dpcd(port))
-		return &port->aux;
-
-	/*
-	 * Synaptics quirk
-	 * Applies to ports for which:
-	 * - Physical aux has Synaptics OUI
-	 * - DPv1.4 or higher
-	 * - Port is on primary branch device
-	 * - Not a VGA adapter (DP_DWN_STRM_PORT_TYPE_ANALOG)
-	 */
-	if (drm_dp_read_desc(port->mgr->aux, &desc, true))
-		return NULL;
-
-	if (drm_dp_has_quirk(&desc, DP_DPCD_QUIRK_DSC_WITHOUT_VIRTUAL_DPCD) &&
-	    port->mgr->dpcd[DP_DPCD_REV] >= DP_DPCD_REV_14 &&
-	    port->parent == port->mgr->mst_primary) {
-		u8 dpcd_ext[DP_RECEIVER_CAP_SIZE];
-
-		if (drm_dp_read_dpcd_caps(port->mgr->aux, dpcd_ext) < 0)
-			return NULL;
-
-		if ((dpcd_ext[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_PRESENT) &&
-		    ((dpcd_ext[DP_DOWNSTREAMPORT_PRESENT] & DP_DWN_STRM_PORT_TYPE_MASK)
-		     != DP_DWN_STRM_PORT_TYPE_ANALOG))
-			return port->mgr->aux;
-	}
-
-	/*
-	 * The check below verifies if the MST sink
-	 * connected to the GPU is capable of DSC -
-	 * therefore the endpoint needs to be
-	 * both DSC and FEC capable.
-	 */
-	if (drm_dp_dpcd_read(&port->aux,
-	   DP_DSC_SUPPORT, &endpoint_dsc, 1) != 1)
-		return NULL;
-	if (drm_dp_dpcd_read(&port->aux,
-	   DP_FEC_CAPABILITY, &endpoint_fec, 1) != 1)
-		return NULL;
-	if ((endpoint_dsc & DP_DSC_DECOMPRESSION_IS_SUPPORTED) &&
-	   (endpoint_fec & DP_FEC_CAPABLE))
-		return &port->aux;
-
-	return NULL;
-}
-EXPORT_SYMBOL(drm_dp_mst_dsc_aux_for_port);