drm/amd/display: Do not program front-end twice

The sequence of front-end > back-end > front-end programming will
program the front-end more than once. Add a mode_changed flag, and use
it to determine whether the front-end should be programmed before, or
after back-end.
Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c

@@ -4009,6 +4009,19 @@ static void amdgpu_dm_commit_planes(struct drm_atomic_state *state,
 	}
 }
 
+/**
+ * amdgpu_dm_crtc_copy_transient_flags - copy mirrored flags from DRM to DC
+ * @crtc_state: the DRM CRTC state
+ * @stream_state: the DC stream state.
+ *
+ * Copy the mirrored transient state flags from DRM, to DC. It is used to bring
+ * a dc_stream_state's flags in sync with a drm_crtc_state's flags.
+ */
+static void amdgpu_dm_crtc_copy_transient_flags(struct drm_crtc_state *crtc_state,
+						struct dc_stream_state *stream_state)
+{
+	stream_state->mode_changed = crtc_state->mode_changed;
+}
 
 static int amdgpu_dm_atomic_commit(struct drm_device *dev,
 				   struct drm_atomic_state *state,
@@ -4079,6 +4092,12 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
 			new_crtc_state->active_changed,
 			new_crtc_state->connectors_changed);
 
+		/* Copy all transient state flags into dc state */
+		if (dm_new_crtc_state->stream) {
+			amdgpu_dm_crtc_copy_transient_flags(&dm_new_crtc_state->base,
+							    dm_new_crtc_state->stream);
+		}
+
 		/* handles headless hotplug case, updating new_state and
 		 * aconnector as needed
 		 */
@@ -4563,6 +4582,7 @@ static int dm_update_crtcs_state(struct dc *dc,
 				WARN_ON(dm_new_crtc_state->stream);
 
 				dm_new_crtc_state->stream = new_stream;
+
 				dc_stream_retain(new_stream);
 
 				DRM_DEBUG_DRIVER("Enabling DRM crtc: %d\n",

drivers/gpu/drm/amd/display/dc/core/dc.c

@@ -672,10 +672,13 @@ static enum dc_status dc_commit_state_no_check(struct dc *dc, struct dc_state *c
 	/* re-program planes for existing stream, in case we need to
 	 * free up plane resource for later use
 	 */
-	for (i = 0; i < dc->current_state->stream_count; i++) {
+	for (i = 0; i < context->stream_count; i++) {
+		if (context->streams[i]->mode_changed)
+			continue;
+
 		dc->hwss.apply_ctx_for_surface(
-			dc, dc->current_state->streams[i],
-			dc->current_state->stream_status[i].plane_count,
+			dc, context->streams[i],
+			context->stream_status[i].plane_count,
 			context); /* use new pipe config in new context */
 	}
 
@@ -701,6 +704,9 @@ static enum dc_status dc_commit_state_no_check(struct dc *dc, struct dc_state *c
 	for (i = 0; i < context->stream_count; i++) {
 		const struct dc_sink *sink = context->streams[i]->sink;
 
+		if (!context->streams[i]->mode_changed)
+			continue;
+
 		dc->hwss.apply_ctx_for_surface(
 				dc, context->streams[i],
 				context->stream_status[i].plane_count,

drivers/gpu/drm/amd/display/dc/dc_stream.h

@@ -92,6 +92,9 @@ struct dc_stream_state {
 
 	struct crtc_trigger_info triggered_crtc_reset;
 
+	/* Computed state bits */
+	bool mode_changed : 1;
+
 };
 
 struct dc_stream_update {