[PATCH 41/73] drm/amd/display: Check aux channel before MST resume

[Harry Wentland]

From: "Jerry (Fangzhi) Zuo" <Jerry.Zuo at amd.com>

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.

Change-Id: I15de6ab99da01841d62912dd98e6cc74d9100801
Signed-off-by: Jerry (Fangzhi) Zuo <Jerry.Zuo at amd.com>
Reviewed-by: Roman Li <Roman.Li at amd.com>
Acked-by: Harry Wentland <harry.wentland at amd.com>
---
 drivers/gpu/drm/amd/display/amdgpu_dm/amdgpu_dm.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

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 bdef1ed0dfac..b88a7cca61a8 100644
--- 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);
 
-- 
2.14.1