drm/amd/display: Check and log for function error codes

[WHAT & HOW]
dm_dmub_hw_init and drm_dp_mst_topology_mgr_set_mst can return error
codes and errors should be reported.

This fixes 2 CHECKED_RETURN issues reported by Coverity.
Reviewed-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Alex Hung <alex.hung@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.c

@@ -1302,6 +1302,7 @@ static void dm_dmub_hw_resume(struct amdgpu_device *adev)
 	struct dmub_srv *dmub_srv = adev->dm.dmub_srv;
 	enum dmub_status status;
 	bool init;
+	int r;
 
 	if (!dmub_srv) {
 		/* DMUB isn't supported on the ASIC. */
@@ -1319,7 +1320,9 @@ static void dm_dmub_hw_resume(struct amdgpu_device *adev)
 			DRM_WARN("Wait for DMUB auto-load failed: %d\n", status);
 	} else {
 		/* Perform the full hardware initialization. */
-		dm_dmub_hw_init(adev);
+		r = dm_dmub_hw_init(adev);
+		if (r)
+			DRM_ERROR("DMUB interface failed to initialize: status=%d\n", r);
 	}
 }
 

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

@@ -3795,6 +3795,7 @@ static int trigger_hpd_mst_set(void *data, u64 val)
 	struct amdgpu_dm_connector *aconnector;
 	struct drm_connector *connector;
 	struct dc_link *link = NULL;
+	int ret;
 
 	if (val == 1) {
 		drm_connector_list_iter_begin(dev, &iter);
@@ -3806,7 +3807,9 @@ static int trigger_hpd_mst_set(void *data, u64 val)
 				dc_link_detect(aconnector->dc_link, DETECT_REASON_HPD);
 				mutex_unlock(&adev->dm.dc_lock);
 
-				drm_dp_mst_topology_mgr_set_mst(&aconnector->mst_mgr, true);
+				ret = drm_dp_mst_topology_mgr_set_mst(&aconnector->mst_mgr, true);
+				if (ret < 0)
+					DRM_ERROR("DM_MST: Failed to set the device into MST mode!");
 			}
 		}
 	} else if (val == 0) {