drm/tilcdc: Add support for drm panels

Add support for drm panels to tilcdc. Adding the support on top of the
existing bridge support needs only couple of lines of code when using
using the drm panel bridge helpers.
Signed-off-by: Jyri Sarha <jsarha@ti.com>
Reviewed-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

drivers/gpu/drm/tilcdc/Kconfig

@@ -4,6 +4,8 @@ config DRM_TILCDC
 	select DRM_KMS_HELPER
 	select DRM_KMS_CMA_HELPER
 	select DRM_GEM_CMA_HELPER
+	select DRM_BRIDGE
+	select DRM_PANEL_BRIDGE
 	select VIDEOMODE_HELPERS
 	select BACKLIGHT_CLASS_DEVICE
 	select BACKLIGHT_LCD_SUPPORT

drivers/gpu/drm/tilcdc/tilcdc_external.c

@@ -188,18 +188,16 @@ int tilcdc_attach_bridge(struct drm_device *ddev, struct drm_bridge *bridge)
 int tilcdc_attach_external_device(struct drm_device *ddev)
 {
 	struct tilcdc_drm_private *priv = ddev->dev_private;
-	struct device_node *remote_node;
 	struct drm_bridge *bridge;
+	struct drm_panel *panel;
 	int ret;
 
-	remote_node = of_graph_get_remote_node(ddev->dev->of_node, 0, 0);
-	if (!remote_node)
+	ret = drm_of_find_panel_or_bridge(ddev->dev->of_node, 0, 0,
+					  &panel, &bridge);
+	if (ret == -ENODEV)
 		return 0;
-
-	bridge = of_drm_find_bridge(remote_node);
-	of_node_put(remote_node);
-	if (!bridge)
-		return -EPROBE_DEFER;
+	else if (ret)
+		return ret;
 
 	priv->external_encoder = devm_kzalloc(ddev->dev,
 					      sizeof(*priv->external_encoder),
@@ -215,10 +213,23 @@ int tilcdc_attach_external_device(struct drm_device *ddev)
 		return ret;
 	}
 
+	if (panel) {
+		bridge = devm_drm_panel_bridge_add(ddev->dev, panel,
+						   DRM_MODE_CONNECTOR_DPI);
+		if (IS_ERR(bridge)) {
+			ret = PTR_ERR(bridge);
+			goto err_encoder_cleanup;
+		}
+	}
+
 	ret = tilcdc_attach_bridge(ddev, bridge);
 	if (ret)
-		drm_encoder_cleanup(priv->external_encoder);
+		goto err_encoder_cleanup;
+
+	return 0;
 
+err_encoder_cleanup:
+	drm_encoder_cleanup(priv->external_encoder);
 	return ret;
 }