drm/fsl-dcu: rework codes to support of_graph dt binding for panel

This patch rework the output code to add of_graph dt binding support
for panel device and also keeps the backward compatibility

Signed-off-by: Meng Yi <meng.yi@nxp.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Stefan Agner <stefan@agner.ch>

Documentation/devicetree/bindings/display/fsl,dcu.txt

@@ -12,7 +12,7 @@ Required properties:
 - clock-names:		Should be "dcu" and "pix"
 			See ../clocks/clock-bindings.txt for details.
 - big-endian		Boolean property, LS1021A DCU registers are big-endian.
-- fsl,panel:		The phandle to panel node.
+- port			Video port for the panel output
 
 Optional properties:
 - fsl,tcon:		The phandle to the timing controller node.
@@ -24,6 +24,11 @@ dcu: dcu@2ce0000 {
 	clocks = <&platform_clk 0>, <&platform_clk 0>;
 	clock-names = "dcu", "pix";
 	big-endian;
-	fsl,panel = <&panel>;
 	fsl,tcon = <&tcon>;
+
+	port {
+		dcu_out: endpoint {
+			remote-endpoint = <&panel_out>;
+	     };
+	};
 };

drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_kms.c

@@ -43,7 +43,7 @@ int fsl_dcu_drm_modeset_init(struct fsl_dcu_drm_device *fsl_dev)
 	if (ret)
 		goto err;
 
-	ret = fsl_dcu_drm_connector_create(fsl_dev, &fsl_dev->encoder);
+	ret = fsl_dcu_create_outputs(fsl_dev);
 	if (ret)
 		goto err;
 

drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_output.h

@@ -25,9 +25,8 @@ to_fsl_dcu_connector(struct drm_connector *con)
 		     : NULL;
 }
 
-int fsl_dcu_drm_connector_create(struct fsl_dcu_drm_device *fsl_dev,
-				 struct drm_encoder *encoder);
 int fsl_dcu_drm_encoder_create(struct fsl_dcu_drm_device *fsl_dev,
 			       struct drm_crtc *crtc);
+int fsl_dcu_create_outputs(struct fsl_dcu_drm_device *fsl_dev);
 
 #endif /* __FSL_DCU_DRM_CONNECTOR_H__ */

drivers/gpu/drm/fsl-dcu/fsl_dcu_drm_rgb.c

@@ -10,6 +10,7 @@
  */
 
 #include <linux/backlight.h>
+#include <linux/of_graph.h>
 
 #include <drm/drmP.h>
 #include <drm/drm_atomic_helper.h>
@@ -132,12 +133,12 @@ static const struct drm_connector_helper_funcs connector_helper_funcs = {
 	.mode_valid = fsl_dcu_drm_connector_mode_valid,
 };
 
-int fsl_dcu_drm_connector_create(struct fsl_dcu_drm_device *fsl_dev,
-				 struct drm_encoder *encoder)
+static int fsl_dcu_attach_panel(struct fsl_dcu_drm_device *fsl_dev,
+				 struct drm_panel *panel)
 {
+	struct drm_encoder *encoder = &fsl_dev->encoder;
 	struct drm_connector *connector = &fsl_dev->connector.base;
 	struct drm_mode_config *mode_config = &fsl_dev->drm->mode_config;
-	struct device_node *panel_node;
 	int ret;
 
 	fsl_dev->connector.encoder = encoder;
@@ -161,21 +162,7 @@ int fsl_dcu_drm_connector_create(struct fsl_dcu_drm_device *fsl_dev,
 				      mode_config->dpms_property,
 				      DRM_MODE_DPMS_OFF);
 
-	panel_node = of_parse_phandle(fsl_dev->np, "fsl,panel", 0);
-	if (!panel_node) {
-		dev_err(fsl_dev->dev, "fsl,panel property not found\n");
-		ret = -ENODEV;
-		goto err_sysfs;
-	}
-
-	fsl_dev->connector.panel = of_drm_find_panel(panel_node);
-	if (!fsl_dev->connector.panel) {
-		ret = -EPROBE_DEFER;
-		goto err_panel;
-	}
-	of_node_put(panel_node);
-
-	ret = drm_panel_attach(fsl_dev->connector.panel, connector);
+	ret = drm_panel_attach(panel, connector);
 	if (ret) {
 		dev_err(fsl_dev->dev, "failed to attach panel\n");
 		goto err_sysfs;
@@ -183,11 +170,52 @@ int fsl_dcu_drm_connector_create(struct fsl_dcu_drm_device *fsl_dev,
 
 	return 0;
 
-err_panel:
-	of_node_put(panel_node);
 err_sysfs:
 	drm_connector_unregister(connector);
 err_cleanup:
 	drm_connector_cleanup(connector);
 	return ret;
 }
+
+static int fsl_dcu_attach_endpoint(struct fsl_dcu_drm_device *fsl_dev,
+				   const struct of_endpoint *ep)
+{
+	struct device_node *np;
+
+	np = of_graph_get_remote_port_parent(ep->local_node);
+
+	fsl_dev->connector.panel = of_drm_find_panel(np);
+	of_node_put(np);
+	if (fsl_dev->connector.panel)
+		return fsl_dcu_attach_panel(fsl_dev, fsl_dev->connector.panel);
+
+	return -ENODEV;
+}
+
+int fsl_dcu_create_outputs(struct fsl_dcu_drm_device *fsl_dev)
+{
+	struct of_endpoint ep;
+	struct device_node *ep_node, *panel_node;
+	int ret;
+
+	/* This is for backward compatibility */
+	panel_node = of_parse_phandle(fsl_dev->np, "fsl,panel", 0);
+	if (panel_node) {
+		fsl_dev->connector.panel = of_drm_find_panel(panel_node);
+		of_node_put(panel_node);
+		if (!fsl_dev->connector.panel)
+			return -EPROBE_DEFER;
+		return fsl_dcu_attach_panel(fsl_dev, fsl_dev->connector.panel);
+	}
+
+	ep_node = of_graph_get_next_endpoint(fsl_dev->np, NULL);
+	if (!ep_node)
+		return -ENODEV;
+
+	ret = of_graph_parse_endpoint(ep_node, &ep);
+	of_node_put(ep_node);
+	if (ret)
+		return -ENODEV;
+
+	return fsl_dcu_attach_endpoint(fsl_dev, &ep);
+}