diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.c b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
index eb7ed8f..1876945 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.c
@@ -110,6 +110,8 @@ static int tilcdc_unload(struct drm_device *dev)
 {
 	struct tilcdc_drm_private *priv = dev->dev_private;
 
+	tilcdc_remove_external_encoders(dev);
+
 	drm_fbdev_cma_fini(priv->fbdev);
 	drm_kms_helper_poll_fini(dev);
 	drm_mode_config_cleanup(dev);
@@ -267,13 +269,13 @@ static int tilcdc_load(struct drm_device *dev, unsigned long flags)
 	if ((priv->num_encoders == 0) || (priv->num_connectors == 0)) {
 		dev_err(dev->dev, "no encoders/connectors found\n");
 		ret = -ENXIO;
-		goto fail_component_cleanup;
+		goto fail_external_cleanup;
 	}
 
 	ret = drm_vblank_init(dev, 1);
 	if (ret < 0) {
 		dev_err(dev->dev, "failed to initialize vblank\n");
-		goto fail_component_cleanup;
+		goto fail_external_cleanup;
 	}
 
 	pm_runtime_get_sync(dev->dev);
@@ -318,6 +320,9 @@ fail_component_cleanup:
 	if (priv->is_componentized)
 		component_unbind_all(dev->dev, dev);
 
+fail_external_cleanup:
+	tilcdc_remove_external_encoders(dev);
+
 fail_cpufreq_unregister:
 	pm_runtime_disable(dev->dev);
 #ifdef CONFIG_CPU_FREQ
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_drv.h b/drivers/gpu/drm/tilcdc/tilcdc_drv.h
index 8ea3d11..ff1c3dd 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_drv.h
+++ b/drivers/gpu/drm/tilcdc/tilcdc_drv.h
@@ -85,6 +85,7 @@ struct tilcdc_drm_private {
 
 	unsigned int num_connectors;
 	struct drm_connector *connectors[8];
+	struct drm_connector_helper_funcs *connector_funcs[8];
 
 	bool is_componentized;
 };
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_external.c b/drivers/gpu/drm/tilcdc/tilcdc_external.c
index 1dd6c20..581b775 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_external.c
+++ b/drivers/gpu/drm/tilcdc/tilcdc_external.c
@@ -27,12 +27,34 @@ static const struct tilcdc_panel_info panel_info_tda998x = {
 		.raster_order           = 0,
 };
 
+static int tilcdc_external_mode_valid(struct drm_connector *connector,
+				      struct drm_display_mode *mode)
+{
+	struct tilcdc_drm_private *priv = connector->dev->dev_private;
+	int ret, i;
+
+	ret = tilcdc_crtc_mode_valid(priv->crtc, mode);
+	if (ret != MODE_OK)
+		return ret;
+
+	for (i = 0; i < priv->num_connectors &&
+		     priv->connectors[i] != connector; i++);
+
+	BUG_ON(priv->connectors[i] != connector);
+
+	if (priv->connector_funcs[i]->mode_valid)
+		return priv->connector_funcs[i]->mode_valid(connector, mode);
+
+	return MODE_OK;
+}
+
 static int tilcdc_add_external_encoder(struct drm_device *dev, int *bpp,
 				       struct drm_connector *connector)
 {
 	struct tilcdc_drm_private *priv = dev->dev_private;
+	struct drm_connector_helper_funcs *connector_funcs;
 
-	priv->connectors[priv->num_connectors++] = connector;
+	priv->connectors[priv->num_connectors] = connector;
 	priv->encoders[priv->num_encoders++] = connector->encoder;
 
 	/* Only tda998x is supported at the moment. */
@@ -40,6 +62,14 @@ static int tilcdc_add_external_encoder(struct drm_device *dev, int *bpp,
 	tilcdc_crtc_set_panel_info(priv->crtc, &panel_info_tda998x);
 	*bpp = panel_info_tda998x.bpp;
 
+	priv->connector_funcs[priv->num_connectors] = connector->helper_private;
+	connector_funcs = devm_kzalloc(dev->dev, sizeof(*connector_funcs),
+				       GFP_KERNEL);
+	*connector_funcs = *priv->connector_funcs[priv->num_connectors];
+	connector_funcs->mode_valid = tilcdc_external_mode_valid;
+	connector->helper_private = connector_funcs;
+	priv->num_connectors++;
+
 	dev_dbg(dev->dev, "External encoder '%s' connected\n",
 		connector->encoder->name);
 
@@ -68,6 +98,17 @@ int tilcdc_add_external_encoders(struct drm_device *dev, int *bpp)
 	return 0;
 }
 
+void tilcdc_remove_external_encoders(struct drm_device *dev)
+{
+	struct tilcdc_drm_private *priv = dev->dev_private;
+	int i;
+
+	for (i = 0; i < priv->num_connectors; i++)
+		if (priv->connector_funcs[i])
+			priv->connectors[i]->helper_private =
+				priv->connector_funcs[i];
+}
+
 static int dev_match_of(struct device *dev, void *data)
 {
 	return dev->of_node == data;
diff --git a/drivers/gpu/drm/tilcdc/tilcdc_external.h b/drivers/gpu/drm/tilcdc/tilcdc_external.h
index 4e7fbf6..685e4dc 100644
--- a/drivers/gpu/drm/tilcdc/tilcdc_external.h
+++ b/drivers/gpu/drm/tilcdc/tilcdc_external.h
@@ -19,6 +19,7 @@
 #define __TILCDC_EXTERNAL_H__
 
 int tilcdc_add_external_encoders(struct drm_device *dev, int *bpp);
+void tilcdc_remove_external_encoders(struct drm_device *dev);
 int tilcdc_get_external_components(struct device *dev,
 				   struct component_match **match);
 #endif /* __TILCDC_SLAVE_H__ */
