drm/i915: Add DSC support to MST path

Whenever we are not able to get enough timeslots
for required PBN, let's try to allocate those
using DSC, just same way as we do for SST.

v2: Removed intel_dp_mst_dsc_compute_config and refactored
    intel_dp_dsc_compute_config to support timeslots as a
    parameter(Ville Syrjälä)

v3: - Rebased
    - Added a debug to see that we at least try reserving
      VCPI slots using DSC, because currently its not visible
      from the logs, thus making debugging more tricky.
    - Moved timeslots to numerator, where it should be.

v4: - Call drm_dp_mst_atomic_check already during link
      config computation, because we need to know already
      by this moment if uncompressed amount of VCPI slots
      needed can fit, otherwise we need to use DSC.
      (thanks to Vinod Govindapillai for pointing this out)

v5: - Put pipe_config->bigjoiner_pipes back to original
      condition in intel_dp_dsc_compute_config
      (don't remember when I lost it)

v6: - Removed unnecessary drm_dp_mst_atomic_check as it is
      now always called in a newly introduced
      intel_dp_mst_find_vcpi_slots_for_bpp function
      (Vinod Govindapillai)

Reviewed-by: Vinod Govindapillai <[email protected]>
Signed-off-by: Stanislav Lisovskiy <[email protected]>
Link: https://patchwork.freedesktop.org/patch/msgid/[email protected]

1 files changed, 125 insertions, 0 deletions

diff --git a/drivers/gpu/drm/i915/display/intel_dp_mst.c b/drivers/gpu/drm/i915/display/intel_dp_mst.c
index 1cdcde56f966..59f80af8d17d 100644
--- a/drivers/gpu/drm/i915/display/intel_dp_mst.c
+++ b/drivers/gpu/drm/i915/display/intel_dp_mst.c
@@ -92,6 +92,7 @@ static int intel_dp_mst_find_vcpi_slots_for_bpp(struct intel_encoder *encoder,
 						      crtc_state->pbn);
 		if (slots == -EDEADLK)
 			return slots;
+
 		if (slots >= 0) {
 			ret = drm_dp_mst_atomic_check(state);
 			/*
@@ -142,6 +143,61 @@ static int intel_dp_mst_compute_link_config(struct intel_encoder *encoder,
 	return 0;
 }
 
+static int intel_dp_dsc_mst_compute_link_config(struct intel_encoder *encoder,
+						struct intel_crtc_state *crtc_state,
+						struct drm_connector_state *conn_state,
+						struct link_config_limits *limits)
+{
+	struct intel_dp_mst_encoder *intel_mst = enc_to_mst(encoder);
+	struct intel_dp *intel_dp = &intel_mst->primary->dp;
+	struct intel_connector *connector =
+		to_intel_connector(conn_state->connector);
+	struct drm_i915_private *i915 = to_i915(connector->base.dev);
+	const struct drm_display_mode *adjusted_mode =
+		&crtc_state->hw.adjusted_mode;
+	int slots = -EINVAL;
+	int i, num_bpc;
+	u8 dsc_bpc[3] = {0};
+	int min_bpp, max_bpp;
+	u8 dsc_max_bpc;
+
+	/* Max DSC Input BPC for ICL is 10 and for TGL+ is 12 */
+	if (DISPLAY_VER(i915) >= 12)
+		dsc_max_bpc = min_t(u8, 12, conn_state->max_requested_bpc);
+	else
+		dsc_max_bpc = min_t(u8, 10, conn_state->max_requested_bpc);
+
+	max_bpp = min_t(u8, dsc_max_bpc * 3, limits->max_bpp);
+	min_bpp = limits->min_bpp;
+
+	num_bpc = drm_dp_dsc_sink_supported_input_bpcs(intel_dp->dsc_dpcd,
+						       dsc_bpc);
+	for (i = 0; i < num_bpc; i++) {
+		if (max_bpp >= dsc_bpc[i] * 3)
+			if (min_bpp > dsc_bpc[i] * 3)
+				min_bpp = dsc_bpc[i] * 3;
+	}
+
+	drm_dbg_kms(&i915->drm, "DSC Sink supported min bpp %d max bpp %d\n",
+		    min_bpp, max_bpp);
+
+	slots = intel_dp_mst_find_vcpi_slots_for_bpp(encoder, crtc_state, max_bpp,
+						     min_bpp, limits,
+						     conn_state, 2 * 3, true);
+
+	if (slots < 0)
+		return slots;
+
+	intel_link_compute_m_n(crtc_state->pipe_bpp,
+			       crtc_state->lane_count,
+			       adjusted_mode->crtc_clock,
+			       crtc_state->port_clock,
+			       &crtc_state->dp_m_n,
+			       crtc_state->fec_enable);
+	crtc_state->dp_m_n.tu = slots;
+
+	return 0;
+}
 static int intel_dp_mst_update_slots(struct intel_encoder *encoder,
 				     struct intel_crtc_state *crtc_state,
 				     struct drm_connector_state *conn_state)
@@ -218,6 +274,29 @@ static int intel_dp_mst_compute_config(struct intel_encoder *encoder,
 
 	ret = intel_dp_mst_compute_link_config(encoder, pipe_config,
 					       conn_state, &limits);
+
+	if (ret == -EDEADLK)
+		return ret;
+
+	/* enable compression if the mode doesn't fit available BW */
+	drm_dbg_kms(&dev_priv->drm, "Force DSC en = %d\n", intel_dp->force_dsc_en);
+	if (ret || intel_dp->force_dsc_en) {
+		/*
+		 * Try to get at least some timeslots and then see, if
+		 * we can fit there with DSC.
+		 */
+		drm_dbg_kms(&dev_priv->drm, "Trying to find VCPI slots in DSC mode\n");
+
+		ret = intel_dp_dsc_mst_compute_link_config(encoder, pipe_config,
+							   conn_state, &limits);
+		if (ret < 0)
+			return ret;
+
+		ret = intel_dp_dsc_compute_config(intel_dp, pipe_config,
+						  conn_state, &limits,
+						  pipe_config->dp_m_n.tu);
+	}
+
 	if (ret)
 		return ret;
 
@@ -728,6 +807,10 @@ intel_dp_mst_mode_valid_ctx(struct drm_connector *connector,
 	int max_dotclk = to_i915(connector->dev)->max_dotclk_freq;
 	int max_rate, mode_rate, max_lanes, max_link_clock;
 	int ret;
+	bool dsc = false, bigjoiner = false;
+	u16 dsc_max_output_bpp = 0;
+	u8 dsc_slice_count = 0;
+	int target_clock = mode->clock;
 
 	if (drm_connector_is_unregistered(connector)) {
 		*status = MODE_ERROR;
@@ -765,6 +848,48 @@ intel_dp_mst_mode_valid_ctx(struct drm_connector *connector,
 		return 0;
 	}
 
+	if (intel_dp_need_bigjoiner(intel_dp, mode->hdisplay, target_clock)) {
+		bigjoiner = true;
+		max_dotclk *= 2;
+	}
+
+	if (DISPLAY_VER(dev_priv) >= 10 &&
+	    drm_dp_sink_supports_dsc(intel_dp->dsc_dpcd)) {
+		/*
+		 * TBD pass the connector BPC,
+		 * for now U8_MAX so that max BPC on that platform would be picked
+		 */
+		int pipe_bpp = intel_dp_dsc_compute_bpp(intel_dp, U8_MAX);
+
+		if (drm_dp_sink_supports_fec(intel_dp->fec_capable)) {
+			dsc_max_output_bpp =
+				intel_dp_dsc_get_output_bpp(dev_priv,
+							    max_link_clock,
+							    max_lanes,
+							    target_clock,
+							    mode->hdisplay,
+							    bigjoiner,
+							    pipe_bpp, 1) >> 4;
+			dsc_slice_count =
+				intel_dp_dsc_get_slice_count(intel_dp,
+							     target_clock,
+							     mode->hdisplay,
+							     bigjoiner);
+		}
+
+		dsc = dsc_max_output_bpp && dsc_slice_count;
+	}
+
+	/*
+	 * Big joiner configuration needs DSC for TGL which is not true for
+	 * XE_LPD where uncompressed joiner is supported.
+	 */
+	if (DISPLAY_VER(dev_priv) < 13 && bigjoiner && !dsc)
+		return MODE_CLOCK_HIGH;
+
+	if (mode_rate > max_rate && !dsc)
+		return MODE_CLOCK_HIGH;
+
 	*status = intel_mode_valid_max_plane_size(dev_priv, mode, false);
 	return 0;
 }