1 files changed, 53 insertions, 2 deletions

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
index e7c7c9b9c646..f08d0fded61f 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
@@ -143,6 +143,7 @@ struct dw_hdmi_phy_data {
 struct dw_hdmi {
 	struct drm_connector connector;
 	struct drm_bridge bridge;
+	struct drm_bridge *next_bridge;
 
 	unsigned int version;
 
@@ -2775,7 +2776,8 @@ static int dw_hdmi_bridge_attach(struct drm_bridge *bridge,
 	struct dw_hdmi *hdmi = bridge->driver_private;
 
 	if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR)
-		return 0;
+		return drm_bridge_attach(bridge->encoder, hdmi->next_bridge,
+					 bridge, flags);
 
 	return dw_hdmi_connector_create(hdmi);
 }
@@ -3160,6 +3162,52 @@ static void dw_hdmi_init_hw(struct dw_hdmi *hdmi)
 /* -----------------------------------------------------------------------------
  * Probe/remove API, used from platforms based on the DRM bridge API.
  */
+
+static int dw_hdmi_parse_dt(struct dw_hdmi *hdmi)
+{
+	struct device_node *endpoint;
+	struct device_node *remote;
+
+	if (!hdmi->plat_data->output_port)
+		return 0;
+
+	endpoint = of_graph_get_endpoint_by_regs(hdmi->dev->of_node,
+						 hdmi->plat_data->output_port,
+						 -1);
+	if (!endpoint) {
+		/*
+		 * On platforms whose bindings don't make the output port
+		 * mandatory (such as Rockchip) the plat_data->output_port
+		 * field isn't set, so it's safe to make this a fatal error.
+		 */
+		dev_err(hdmi->dev, "Missing endpoint in port@%u\n",
+			hdmi->plat_data->output_port);
+		return -ENODEV;
+	}
+
+	remote = of_graph_get_remote_port_parent(endpoint);
+	of_node_put(endpoint);
+	if (!remote) {
+		dev_err(hdmi->dev, "Endpoint in port@%u unconnected\n",
+			hdmi->plat_data->output_port);
+		return -ENODEV;
+	}
+
+	if (!of_device_is_available(remote)) {
+		dev_err(hdmi->dev, "port@%u remote device is disabled\n",
+			hdmi->plat_data->output_port);
+		of_node_put(remote);
+		return -ENODEV;
+	}
+
+	hdmi->next_bridge = of_drm_find_bridge(remote);
+	of_node_put(remote);
+	if (!hdmi->next_bridge)
+		return -EPROBE_DEFER;
+
+	return 0;
+}
+
 struct dw_hdmi *dw_hdmi_probe(struct platform_device *pdev,
 			      const struct dw_hdmi_plat_data *plat_data)
 {
@@ -3196,6 +3244,10 @@ struct dw_hdmi *dw_hdmi_probe(struct platform_device *pdev,
 	mutex_init(&hdmi->cec_notifier_mutex);
 	spin_lock_init(&hdmi->audio_lock);
 
+	ret = dw_hdmi_parse_dt(hdmi);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
 	ddc_node = of_parse_phandle(np, "ddc-i2c-bus", 0);
 	if (ddc_node) {
 		hdmi->ddc = of_get_i2c_adapter_by_node(ddc_node);
@@ -3474,7 +3526,6 @@ struct dw_hdmi *dw_hdmi_bind(struct platform_device *pdev,
 	ret = drm_bridge_attach(encoder, &hdmi->bridge, NULL, 0);
 	if (ret) {
 		dw_hdmi_remove(hdmi);
-		DRM_ERROR("Failed to initialize bridge with drm\n");
 		return ERR_PTR(ret);
 	}