drm/dp/mst: Restore primary hub guid on resume

[karo-tx-linux.git] / drivers / gpu / drm / drm_dp_mst_topology.c

diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index a4a3de372b693aedf32dea2f467700a8f09790ca..04350dfa49599ca29bed75932caa7712412f2570 100644 (file)
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -2116,6 +2116,8 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr)
 
        if (mgr->mst_primary) {
                int sret;
+               u8 guid[16];
+
                sret = drm_dp_dpcd_read(mgr->aux, DP_DPCD_REV, mgr->dpcd, DP_RECEIVER_CAP_SIZE);
                if (sret != DP_RECEIVER_CAP_SIZE) {
                        DRM_DEBUG_KMS("dpcd read failed - undocked during suspend?\n");
@@ -2130,6 +2132,16 @@ int drm_dp_mst_topology_mgr_resume(struct drm_dp_mst_topology_mgr *mgr)
                        ret = -1;
                        goto out_unlock;
                }
+
+               /* Some hubs forget their guids after they resume */
+               sret = drm_dp_dpcd_read(mgr->aux, DP_GUID, guid, 16);
+               if (sret != 16) {
+                       DRM_DEBUG_KMS("dpcd read failed - undocked during suspend?\n");
+                       ret = -1;
+                       goto out_unlock;
+               }
+               drm_dp_check_mstb_guid(mgr->mst_primary, guid);
+
                ret = 0;
        } else
                ret = -1;