drm/amd/display: Simplify underscan and ABM commit

[Why]
Underscan and ABM are connector properties but require updates
to DC stream state.  Previously, on updates to these properties
the affected stream and all its planes were committed.
This is unnecessary; only a few fields on the stream need
to be changed.

[How]
If scaling or ABM have changed, change the stream and
create a stream update with those changes.  Call
DC with only those fields.
Signed-off-by: David Francis <David.Francis@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Reviewed-by: Nicholas Kazlauskas <Nicholas.Kazlauskas@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -5160,11 +5160,13 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
 		}
 	}
 
-	/* Handle scaling, underscan, and abm changes*/
+	/* Handle connector state changes */
 	for_each_oldnew_connector_in_state(state, connector, old_con_state, new_con_state, i) {
 		struct dm_connector_state *dm_new_con_state = to_dm_connector_state(new_con_state);
 		struct dm_connector_state *dm_old_con_state = to_dm_connector_state(old_con_state);
 		struct amdgpu_crtc *acrtc = to_amdgpu_crtc(dm_new_con_state->base.crtc);
+		struct dc_surface_update dummy_updates[MAX_SURFACES] = { 0 };
+		struct dc_stream_update stream_update = { 0 };
 		struct dc_stream_status *status = NULL;
 
 		if (acrtc) {
@@ -5176,37 +5178,48 @@ static void amdgpu_dm_atomic_commit_tail(struct drm_atomic_state *state)
 		if (!acrtc || drm_atomic_crtc_needs_modeset(new_crtc_state))
 			continue;
 
-
 		dm_new_crtc_state = to_dm_crtc_state(new_crtc_state);
 		dm_old_crtc_state = to_dm_crtc_state(old_crtc_state);
 
-		/* Skip anything that is not scaling or underscan changes */
 		if (!is_scaling_state_different(dm_new_con_state, dm_old_con_state) &&
 				(dm_new_crtc_state->abm_level == dm_old_crtc_state->abm_level))
 			continue;
 
-		update_stream_scaling_settings(&dm_new_con_state->base.crtc->mode,
-				dm_new_con_state, (struct dc_stream_state *)dm_new_crtc_state->stream);
+		if (is_scaling_state_different(dm_new_con_state, dm_old_con_state)) {
+			update_stream_scaling_settings(&dm_new_con_state->base.crtc->mode,
+					dm_new_con_state, (struct dc_stream_state *)dm_new_crtc_state->stream);
 
-		if (!dm_new_crtc_state->stream)
-			continue;
+			stream_update.src = dm_new_crtc_state->stream->src;
+			stream_update.dst = dm_new_crtc_state->stream->dst;
+		}
+
+		if (dm_new_crtc_state->abm_level != dm_old_crtc_state->abm_level) {
+			dm_new_crtc_state->stream->abm_level = dm_new_crtc_state->abm_level;
+
+			stream_update.abm_level = &dm_new_crtc_state->abm_level;
+		}
 
 		status = dc_stream_get_status(dm_new_crtc_state->stream);
 		WARN_ON(!status);
 		WARN_ON(!status->plane_count);
 
-		dm_new_crtc_state->stream->abm_level = dm_new_crtc_state->abm_level;
+		/*
+		 * TODO: DC refuses to perform stream updates without a dc_surface_update.
+		 * Here we create an empty update on each plane.
+		 * To fix this, DC should permit updating only stream properties.
+		 */
+		for (j = 0; j < status->plane_count; j++)
+			dummy_updates[j].surface = status->plane_states[0];
 
-		/*TODO How it works with MPO ?*/
-		if (!commit_planes_to_stream(
-				dm,
-				dm->dc,
-				status->plane_states,
-				status->plane_count,
-				dm_new_crtc_state,
-				to_dm_crtc_state(old_crtc_state),
-				dc_state))
-			dm_error("%s: Failed to update stream scaling!\n", __func__);
+
+		mutex_lock(&dm->dc_lock);
+		dc_commit_updates_for_stream(dm->dc,
+						     dummy_updates,
+						     status->plane_count,
+						     dm_new_crtc_state->stream,
+						     &stream_update,
+						     dc_state);
+		mutex_unlock(&dm->dc_lock);
 	}
 
 	for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state,