diff --git a/drivers/gpu/drm/drm_probe_helper.c b/drivers/gpu/drm/drm_probe_helper.c
index 0dd23a7193e7..425f56280d51 100644
--- a/drivers/gpu/drm/drm_probe_helper.c
+++ b/drivers/gpu/drm/drm_probe_helper.c
@@ -476,7 +476,6 @@ int drm_helper_probe_single_connector_modes(struct drm_connector *connector,
 	const struct drm_connector_helper_funcs *connector_funcs =
 		connector->helper_private;
 	int count = 0, ret;
-	bool verbose_prune = true;
 	enum drm_connector_status old_status;
 	struct drm_modeset_acquire_ctx ctx;
 
@@ -556,8 +555,8 @@ retry:
 		DRM_DEBUG_KMS("[CONNECTOR:%d:%s] disconnected\n",
 			connector->base.id, connector->name);
 		drm_connector_update_edid_property(connector, NULL);
-		verbose_prune = false;
-		goto prune;
+		drm_mode_prune_invalid(dev, &connector->modes, false);
+		goto exit;
 	}
 
 	count = (*connector_funcs->get_modes)(connector);
@@ -581,9 +580,27 @@ retry:
 		}
 	}
 
-prune:
-	drm_mode_prune_invalid(dev, &connector->modes, verbose_prune);
+	drm_mode_prune_invalid(dev, &connector->modes, true);
 
+	/*
+	 * Displayport spec section 5.2.1.2 ("Video Timing Format") says that
+	 * all detachable sinks shall support 640x480 @60Hz as a fail safe
+	 * mode. If all modes were pruned, perhaps because they need more
+	 * lanes or a higher pixel clock than available, at least try to add
+	 * in 640x480.
+	 */
+	if (list_empty(&connector->modes) &&
+	    connector->connector_type == DRM_MODE_CONNECTOR_DisplayPort) {
+		count = drm_add_modes_noedid(connector, 640, 480);
+		ret = __drm_helper_update_and_validate(connector, maxX, maxY, &ctx);
+		if (ret == -EDEADLK) {
+			drm_modeset_backoff(&ctx);
+			goto retry;
+		}
+		drm_mode_prune_invalid(dev, &connector->modes, true);
+	}
+
+exit:
 	drm_modeset_drop_locks(&ctx);
 	drm_modeset_acquire_fini(&ctx);