drm/amd/display: Check aux channel before MST resume

It is to fix: MST display failed to resume from S3

At the beginning of resume from S3, need to check if mgr->aux is
NULL. Fake MST encoder doesn't have real aux channel.

Signed-off-by: Jerry (Fangzhi) Zuo <Jerry.Zuo@amd.com>
Reviewed-by: Roman Li <Roman.Li@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
index 009aaeb..5293604 100644 (file)
--- a/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
+++ b/drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c
@@ -520,7 +520,8 @@ static int detect_mst_link_for_all_connectors(struct drm_device *dev)
 
        list_for_each_entry(connector, &dev->mode_config.connector_list, head) {
                aconnector = to_amdgpu_dm_connector(connector);
-               if (aconnector->dc_link->type == dc_connection_mst_branch) {
+               if (aconnector->dc_link->type == dc_connection_mst_branch &&
+                   aconnector->mst_mgr.aux) {
                        DRM_DEBUG_DRIVER("DM_MST: starting TM on aconnector: %p [id: %d]\n",
                                        aconnector, aconnector->base.base.id);