drm/amd/display: dsc mst re-compute pbn for changes on hub

[why]
when unplug 1 dp from dsc mst hub, atomic_check new request
dc_state only include info for the unplug dp. this will not
trigger re-compute pbn for displays still connected to hub.

[how] all displays connected to dsc hub are available in
dc->current_state, by comparing dc->current_state and new
request from atomic_chceck, it will provide info of
displays connected to hub and do pbn re-compute.
Reviewed-by: Roman Li <Roman.Li@amd.com>
Acked-by: Jasdeep Dhillon <jdhillon@amd.com>
Signed-off-by: Hersen Wu <hersenwu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

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

@@ -911,22 +911,31 @@ static bool is_dsc_need_re_compute(
 	struct dc_state *dc_state,
 	struct dc_link *dc_link)
 {
-	int i;
+	int i, j;
 	bool is_dsc_need_re_compute = false;
+	struct amdgpu_dm_connector *stream_on_link[MAX_PIPES];
+	int new_stream_on_link_num = 0;
+	struct amdgpu_dm_connector *aconnector;
+	struct dc_stream_state *stream;
+	const struct dc *dc = dc_link->dc;
 
-	/* only check phy used by mst branch */
+	/* only check phy used by dsc mst branch */
 	if (dc_link->type != dc_connection_mst_branch)
 		return false;
 
+	if (!(dc_link->dpcd_caps.dsc_caps.dsc_basic_caps.fields.dsc_support.DSC_SUPPORT ||
+		dc_link->dpcd_caps.dsc_caps.dsc_basic_caps.fields.dsc_support.DSC_PASSTHROUGH_SUPPORT))
+		return false;
+
+	for (i = 0; i < MAX_PIPES; i++)
+		stream_on_link[i] = NULL;
+
 	/* check if there is mode change in new request */
 	for (i = 0; i < dc_state->stream_count; i++) {
-		struct amdgpu_dm_connector *aconnector;
-		struct dc_stream_state *stream;
 		struct drm_crtc_state *new_crtc_state;
 		struct drm_connector_state *new_conn_state;
 
 		stream = dc_state->streams[i];
-
 		if (!stream)
 			continue;
 
@@ -938,8 +947,10 @@ static bool is_dsc_need_re_compute(
 		if (!aconnector)
 			continue;
 
-		new_conn_state = drm_atomic_get_new_connector_state(state, &aconnector->base);
+		stream_on_link[new_stream_on_link_num] = aconnector;
+		new_stream_on_link_num++;
 
+		new_conn_state = drm_atomic_get_new_connector_state(state, &aconnector->base);
 		if (!new_conn_state)
 			continue;
 
@@ -950,7 +961,6 @@ static bool is_dsc_need_re_compute(
 			continue;
 
 		new_crtc_state = drm_atomic_get_new_crtc_state(state, new_conn_state->crtc);
-
 		if (!new_crtc_state)
 			continue;
 
@@ -960,7 +970,34 @@ static bool is_dsc_need_re_compute(
 		if (new_crtc_state->enable && new_crtc_state->active) {
 			if (new_crtc_state->mode_changed || new_crtc_state->active_changed ||
 				new_crtc_state->connectors_changed)
+				return true;
+		}
+	}
+
+	/* check current_state if there stream on link but it is not in
+	 * new request state
+	 */
+	for (i = 0; i < dc->current_state->stream_count; i++) {
+		stream = dc->current_state->streams[i];
+		/* only check stream on the mst hub */
+		if (stream->link != dc_link)
+			continue;
+
+		aconnector = (struct amdgpu_dm_connector *)stream->dm_stream_context;
+		if (!aconnector)
+			continue;
+
+		for (j = 0; j < new_stream_on_link_num; j++) {
+			if (stream_on_link[j]) {
+				if (aconnector == stream_on_link[j])
+					break;
+			}
+		}
+
+		if (j == new_stream_on_link_num) {
+			/* not in new state */
 			is_dsc_need_re_compute = true;
+			break;
 		}
 	}