drm: sti: allow to change hdmi ddc i2c adapter

Depending of the board configuration i2c for ddc could change,
this patch allow to use a phandle to specify which i2c controller to use.
Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>

Documentation/devicetree/bindings/gpu/st,stih4xx.txt

@@ -69,6 +69,7 @@ STMicroelectronics stih4xx platforms
   - clock-names: names of the clocks listed in clocks property in the same
     order.
   - hdmi,hpd-gpio: gpio id to detect if an hdmi cable is plugged or not.
+  - ddc: phandle of an I2C controller used for DDC EDID probing
 
 sti-hda:
   Required properties:

drivers/gpu/drm/sti/sti_hdmi.c

@@ -480,17 +480,15 @@ static const struct drm_bridge_funcs sti_hdmi_bridge_funcs = {
 
 static int sti_hdmi_connector_get_modes(struct drm_connector *connector)
 {
-	struct i2c_adapter *i2c_adap;
+	struct sti_hdmi_connector *hdmi_connector
+		= to_sti_hdmi_connector(connector);
+	struct sti_hdmi *hdmi = hdmi_connector->hdmi;
 	struct edid *edid;
 	int count;
 
 	DRM_DEBUG_DRIVER("\n");
 
-	i2c_adap = i2c_get_adapter(1);
-	if (!i2c_adap)
-		goto fail;
-
-	edid = drm_get_edid(connector, i2c_adap);
+	edid = drm_get_edid(connector, hdmi->ddc_adapt);
 	if (!edid)
 		goto fail;
 
@@ -603,29 +601,38 @@ static int sti_hdmi_bind(struct device *dev, struct device *master, void *data)
 	struct sti_hdmi_connector *connector;
 	struct drm_connector *drm_connector;
 	struct drm_bridge *bridge;
-	struct i2c_adapter *i2c_adap;
+	struct device_node *ddc;
 	int err;
 
-	i2c_adap = i2c_get_adapter(1);
-	if (!i2c_adap)
-		return -EPROBE_DEFER;
+	ddc = of_parse_phandle(dev->of_node, "ddc", 0);
+	if (ddc) {
+		hdmi->ddc_adapt = of_find_i2c_adapter_by_node(ddc);
+		if (!hdmi->ddc_adapt) {
+			err = -EPROBE_DEFER;
+			of_node_put(ddc);
+			return err;
+		}
+
+		of_node_put(ddc);
+	}
 
 	/* Set the drm device handle */
 	hdmi->drm_dev = drm_dev;
 
 	encoder = sti_hdmi_find_encoder(drm_dev);
 	if (!encoder)
-		return -ENOMEM;
+		goto err_adapt;
 
 	connector = devm_kzalloc(dev, sizeof(*connector), GFP_KERNEL);
 	if (!connector)
-		return -ENOMEM;
+		goto err_adapt;
+
 
 	connector->hdmi = hdmi;
 
 	bridge = devm_kzalloc(dev, sizeof(*bridge), GFP_KERNEL);
 	if (!bridge)
-		return -ENOMEM;
+		goto err_adapt;
 
 	bridge->driver_private = hdmi;
 	drm_bridge_init(drm_dev, bridge, &sti_hdmi_bridge_funcs);
@@ -662,6 +669,8 @@ static int sti_hdmi_bind(struct device *dev, struct device *master, void *data)
 err_connector:
 	drm_bridge_cleanup(bridge);
 	drm_connector_cleanup(drm_connector);
+err_adapt:
+	put_device(&hdmi->ddc_adapt->dev);
 	return -EINVAL;
 }
 
@@ -788,6 +797,11 @@ static int sti_hdmi_probe(struct platform_device *pdev)
 
 static int sti_hdmi_remove(struct platform_device *pdev)
 {
+	struct sti_hdmi *hdmi = dev_get_drvdata(&pdev->dev);
+
+	if (hdmi->ddc_adapt)
+		put_device(&hdmi->ddc_adapt->dev);
+
 	component_del(&pdev->dev, &sti_hdmi_ops);
 	return 0;
 }

drivers/gpu/drm/sti/sti_hdmi.h

@@ -62,6 +62,7 @@ struct sti_hdmi {
 	wait_queue_head_t wait_event;
 	bool event_received;
 	struct reset_control *reset;
+	struct i2c_adapter *ddc_adapt;
 };
 
 u32 hdmi_read(struct sti_hdmi *hdmi, int offset);