1 files changed, 160 insertions, 134 deletions

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 1545c50fd1c8..c3d69af02e79 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -153,6 +153,45 @@
  * situation when probing.
  */
 
+/**
+ * DOC: dsi bridge operations
+ *
+ * DSI host interfaces are expected to be implemented as bridges rather than
+ * encoders, however there are a few aspects of their operation that need to
+ * be defined in order to provide a consistent interface.
+ *
+ * A DSI host should keep the PHY powered down until the pre_enable operation is
+ * called. All lanes are in an undefined idle state up to this point, and it
+ * must not be assumed that it is LP-11.
+ * pre_enable should initialise the PHY, set the data lanes to LP-11, and the
+ * clock lane to either LP-11 or HS depending on the mode_flag
+ * %MIPI_DSI_CLOCK_NON_CONTINUOUS.
+ *
+ * Ordinarily the downstream bridge DSI peripheral pre_enable will have been
+ * called before the DSI host. If the DSI peripheral requires LP-11 and/or
+ * the clock lane to be in HS mode prior to pre_enable, then it can set the
+ * &pre_enable_prev_first flag to request the pre_enable (and
+ * post_disable) order to be altered to enable the DSI host first.
+ *
+ * Either the CRTC being enabled, or the DSI host enable operation should switch
+ * the host to actively transmitting video on the data lanes.
+ *
+ * The reverse also applies. The DSI host disable operation or stopping the CRTC
+ * should stop transmitting video, and the data lanes should return to the LP-11
+ * state. The DSI host &post_disable operation should disable the PHY.
+ * If the &pre_enable_prev_first flag is set, then the DSI peripheral's
+ * bridge &post_disable will be called before the DSI host's post_disable.
+ *
+ * Whilst it is valid to call &host_transfer prior to pre_enable or after
+ * post_disable, the exact state of the lanes is undefined at this point. The
+ * DSI host should initialise the interface, transmit the data, and then disable
+ * the interface again.
+ *
+ * Ultra Low Power State (ULPS) is not explicitly supported by DRM. If
+ * implemented, it therefore needs to be handled entirely within the DSI Host
+ * driver.
+ */
+
 static DEFINE_MUTEX(bridge_lock);
 static LIST_HEAD(bridge_list);
 
@@ -510,61 +549,6 @@ drm_bridge_chain_mode_valid(struct drm_bridge *bridge,
 EXPORT_SYMBOL(drm_bridge_chain_mode_valid);
 
 /**
- * drm_bridge_chain_disable - disables all bridges in the encoder chain
- * @bridge: bridge control structure
- *
- * Calls &drm_bridge_funcs.disable op for all the bridges in the encoder
- * chain, starting from the last bridge to the first. These are called before
- * calling the encoder's prepare op.
- *
- * Note: the bridge passed should be the one closest to the encoder
- */
-void drm_bridge_chain_disable(struct drm_bridge *bridge)
-{
-	struct drm_encoder *encoder;
-	struct drm_bridge *iter;
-
-	if (!bridge)
-		return;
-
-	encoder = bridge->encoder;
-	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
-		if (iter->funcs->disable)
-			iter->funcs->disable(iter);
-
-		if (iter == bridge)
-			break;
-	}
-}
-EXPORT_SYMBOL(drm_bridge_chain_disable);
-
-/**
- * drm_bridge_chain_post_disable - cleans up after disabling all bridges in the
- *				   encoder chain
- * @bridge: bridge control structure
- *
- * Calls &drm_bridge_funcs.post_disable op for all the bridges in the
- * encoder chain, starting from the first bridge to the last. These are called
- * after completing the encoder's prepare op.
- *
- * Note: the bridge passed should be the one closest to the encoder
- */
-void drm_bridge_chain_post_disable(struct drm_bridge *bridge)
-{
-	struct drm_encoder *encoder;
-
-	if (!bridge)
-		return;
-
-	encoder = bridge->encoder;
-	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
-		if (bridge->funcs->post_disable)
-			bridge->funcs->post_disable(bridge);
-	}
-}
-EXPORT_SYMBOL(drm_bridge_chain_post_disable);
-
-/**
  * drm_bridge_chain_mode_set - set proposed mode for all bridges in the
  *			       encoder chain
  * @bridge: bridge control structure
@@ -594,61 +578,6 @@ void drm_bridge_chain_mode_set(struct drm_bridge *bridge,
 EXPORT_SYMBOL(drm_bridge_chain_mode_set);
 
 /**
- * drm_bridge_chain_pre_enable - prepares for enabling all bridges in the
- *				 encoder chain
- * @bridge: bridge control structure
- *
- * Calls &drm_bridge_funcs.pre_enable op for all the bridges in the encoder
- * chain, starting from the last bridge to the first. These are called
- * before calling the encoder's commit op.
- *
- * Note: the bridge passed should be the one closest to the encoder
- */
-void drm_bridge_chain_pre_enable(struct drm_bridge *bridge)
-{
-	struct drm_encoder *encoder;
-	struct drm_bridge *iter;
-
-	if (!bridge)
-		return;
-
-	encoder = bridge->encoder;
-	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
-		if (iter->funcs->pre_enable)
-			iter->funcs->pre_enable(iter);
-
-		if (iter == bridge)
-			break;
-	}
-}
-EXPORT_SYMBOL(drm_bridge_chain_pre_enable);
-
-/**
- * drm_bridge_chain_enable - enables all bridges in the encoder chain
- * @bridge: bridge control structure
- *
- * Calls &drm_bridge_funcs.enable op for all the bridges in the encoder
- * chain, starting from the first bridge to the last. These are called
- * after completing the encoder's commit op.
- *
- * Note that the bridge passed should be the one closest to the encoder
- */
-void drm_bridge_chain_enable(struct drm_bridge *bridge)
-{
-	struct drm_encoder *encoder;
-
-	if (!bridge)
-		return;
-
-	encoder = bridge->encoder;
-	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
-		if (bridge->funcs->enable)
-			bridge->funcs->enable(bridge);
-	}
-}
-EXPORT_SYMBOL(drm_bridge_chain_enable);
-
-/**
  * drm_atomic_bridge_chain_disable - disables all bridges in the encoder chain
  * @bridge: bridge control structure
  * @old_state: old atomic state
@@ -691,6 +620,25 @@ void drm_atomic_bridge_chain_disable(struct drm_bridge *bridge,
 }
 EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
 
+static void drm_atomic_bridge_call_post_disable(struct drm_bridge *bridge,
+						struct drm_atomic_state *old_state)
+{
+	if (old_state && bridge->funcs->atomic_post_disable) {
+		struct drm_bridge_state *old_bridge_state;
+
+		old_bridge_state =
+			drm_atomic_get_old_bridge_state(old_state,
+							bridge);
+		if (WARN_ON(!old_bridge_state))
+			return;
+
+		bridge->funcs->atomic_post_disable(bridge,
+						   old_bridge_state);
+	} else if (bridge->funcs->post_disable) {
+		bridge->funcs->post_disable(bridge);
+	}
+}
+
 /**
  * drm_atomic_bridge_chain_post_disable - cleans up after disabling all bridges
  *					  in the encoder chain
@@ -702,36 +650,86 @@ EXPORT_SYMBOL(drm_atomic_bridge_chain_disable);
  * starting from the first bridge to the last. These are called after completing
  * &drm_encoder_helper_funcs.atomic_disable
  *
+ * If a bridge sets @pre_enable_prev_first, then the @post_disable for that
+ * bridge will be called before the previous one to reverse the @pre_enable
+ * calling direction.
+ *
  * Note: the bridge passed should be the one closest to the encoder
  */
 void drm_atomic_bridge_chain_post_disable(struct drm_bridge *bridge,
 					  struct drm_atomic_state *old_state)
 {
 	struct drm_encoder *encoder;
+	struct drm_bridge *next, *limit;
 
 	if (!bridge)
 		return;
 
 	encoder = bridge->encoder;
+
 	list_for_each_entry_from(bridge, &encoder->bridge_chain, chain_node) {
-		if (bridge->funcs->atomic_post_disable) {
-			struct drm_bridge_state *old_bridge_state;
+		limit = NULL;
+
+		if (!list_is_last(&bridge->chain_node, &encoder->bridge_chain)) {
+			next = list_next_entry(bridge, chain_node);
+
+			if (next->pre_enable_prev_first) {
+				/* next bridge had requested that prev
+				 * was enabled first, so disabled last
+				 */
+				limit = next;
+
+				/* Find the next bridge that has NOT requested
+				 * prev to be enabled first / disabled last
+				 */
+				list_for_each_entry_from(next, &encoder->bridge_chain,
+							 chain_node) {
+					if (next->pre_enable_prev_first) {
+						next = list_prev_entry(next, chain_node);
+						limit = next;
+						break;
+					}
+				}
+
+				/* Call these bridges in reverse order */
+				list_for_each_entry_from_reverse(next, &encoder->bridge_chain,
+								 chain_node) {
+					if (next == bridge)
+						break;
+
+					drm_atomic_bridge_call_post_disable(next,
+									    old_state);
+				}
+			}
+		}
 
-			old_bridge_state =
-				drm_atomic_get_old_bridge_state(old_state,
-								bridge);
-			if (WARN_ON(!old_bridge_state))
-				return;
+		drm_atomic_bridge_call_post_disable(bridge, old_state);
 
-			bridge->funcs->atomic_post_disable(bridge,
-							   old_bridge_state);
-		} else if (bridge->funcs->post_disable) {
-			bridge->funcs->post_disable(bridge);
-		}
+		if (limit)
+			/* Jump all bridges that we have already post_disabled */
+			bridge = limit;
 	}
 }
 EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
 
+static void drm_atomic_bridge_call_pre_enable(struct drm_bridge *bridge,
+					      struct drm_atomic_state *old_state)
+{
+	if (old_state && bridge->funcs->atomic_pre_enable) {
+		struct drm_bridge_state *old_bridge_state;
+
+		old_bridge_state =
+			drm_atomic_get_old_bridge_state(old_state,
+							bridge);
+		if (WARN_ON(!old_bridge_state))
+			return;
+
+		bridge->funcs->atomic_pre_enable(bridge, old_bridge_state);
+	} else if (bridge->funcs->pre_enable) {
+		bridge->funcs->pre_enable(bridge);
+	}
+}
+
 /**
  * drm_atomic_bridge_chain_pre_enable - prepares for enabling all bridges in
  *					the encoder chain
@@ -743,32 +741,60 @@ EXPORT_SYMBOL(drm_atomic_bridge_chain_post_disable);
  * starting from the last bridge to the first. These are called before calling
  * &drm_encoder_helper_funcs.atomic_enable
  *
+ * If a bridge sets @pre_enable_prev_first, then the pre_enable for the
+ * prev bridge will be called before pre_enable of this bridge.
+ *
  * Note: the bridge passed should be the one closest to the encoder
  */
 void drm_atomic_bridge_chain_pre_enable(struct drm_bridge *bridge,
 					struct drm_atomic_state *old_state)
 {
 	struct drm_encoder *encoder;
-	struct drm_bridge *iter;
+	struct drm_bridge *iter, *next, *limit;
 
 	if (!bridge)
 		return;
 
 	encoder = bridge->encoder;
+
 	list_for_each_entry_reverse(iter, &encoder->bridge_chain, chain_node) {
-		if (iter->funcs->atomic_pre_enable) {
-			struct drm_bridge_state *old_bridge_state;
+		if (iter->pre_enable_prev_first) {
+			next = iter;
+			limit = bridge;
+			list_for_each_entry_from_reverse(next,
+							 &encoder->bridge_chain,
+							 chain_node) {
+				if (next == bridge)
+					break;
+
+				if (!next->pre_enable_prev_first) {
+					/* Found first bridge that does NOT
+					 * request prev to be enabled first
+					 */
+					limit = list_prev_entry(next, chain_node);
+					break;
+				}
+			}
+
+			list_for_each_entry_from(next, &encoder->bridge_chain, chain_node) {
+				/* Call requested prev bridge pre_enable
+				 * in order.
+				 */
+				if (next == iter)
+					/* At the first bridge to request prev
+					 * bridges called first.
+					 */
+					break;
+
+				drm_atomic_bridge_call_pre_enable(next, old_state);
+			}
+		}
 
-			old_bridge_state =
-				drm_atomic_get_old_bridge_state(old_state,
-								iter);
-			if (WARN_ON(!old_bridge_state))
-				return;
+		drm_atomic_bridge_call_pre_enable(iter, old_state);
 
-			iter->funcs->atomic_pre_enable(iter, old_bridge_state);
-		} else if (iter->funcs->pre_enable) {
-			iter->funcs->pre_enable(iter);
-		}
+		if (iter->pre_enable_prev_first)
+			/* Jump all bridges that we have already pre_enabled */
+			iter = limit;
 
 		if (iter == bridge)
 			break;