diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c
index 7ce9e212770a..b7fce0bf8acc 100644
--- a/drivers/gpu/drm/display/drm_dp_mst_topology.c
+++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c
@@ -2161,6 +2161,9 @@ ssize_t drm_dp_mst_dpcd_read(struct drm_dp_aux *aux,
 	struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port,
 						    aux);
 
+	if (!port->ddps)
+		return -EIO;
+
 	return drm_dp_send_dpcd_read(port->mgr, port,
 				     offset, size, buffer);
 }
@@ -2184,6 +2187,9 @@ ssize_t drm_dp_mst_dpcd_write(struct drm_dp_aux *aux,
 	struct drm_dp_mst_port *port = container_of(aux, struct drm_dp_mst_port,
 						    aux);
 
+	if (!port->ddps)
+		return -EIO;
+
 	return drm_dp_send_dpcd_write(port->mgr, port,
 				      offset, size, buffer);
 }