diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c
index e23df5fd3836b1b70169a1ee125782c1e754b875..e4c9b4a68c046a2353960e202848112368863a5e 100644
--- a/drivers/gpu/drm/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/drm_dp_mst_topology.c
@@ -1182,17 +1182,18 @@ static struct drm_dp_mst_branch *drm_dp_get_mst_branch_device(struct drm_dp_mst_
 
 		list_for_each_entry(port, &mstb->ports, next) {
 			if (port->port_num == port_num) {
-				if (!port->mstb) {
+				mstb = port->mstb;
+				if (!mstb) {
 					DRM_ERROR("failed to lookup MSTB with lct %d, rad %02x\n", lct, rad[0]);
-					return NULL;
+					goto out;
 				}
 
-				mstb = port->mstb;
 				break;
 			}
 		}
 	}
 	kref_get(&mstb->kref);
+out:
 	mutex_unlock(&mgr->lock);
 	return mstb;
 }