drm/drm_of: add drm_of_panel_bridge_remove function

This function is the pendant of drm_of_find_panel_or_bridge()
to remove a previously allocated panel_bridge.
Given a specific port and endpoint it remove the panel bridge.
Since drm_panel_bridge_remove() will check that bridge parameter
is not NULL and is a real drm_panel_bridge and no a simple bridge
it is safe to call it directly.

Signed-off-by: Benjamin Gaignard <benjamin.gaignard@linaro.org>
Reviewed-by: Philippe Cornu <philippe.cornu@st.com>
Tested-by: Philippe Cornu <philippe.cornu@st.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1506936888-23844-3-git-send-email-benjamin.gaignard@linaro.org

drivers/gpu/drm/drm_of.c

@@ -262,3 +262,36 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
 	return ret;
 }
 EXPORT_SYMBOL_GPL(drm_of_find_panel_or_bridge);
+
+#ifdef CONFIG_DRM_PANEL_BRIDGE
+/*
+ * drm_of_panel_bridge_remove - remove panel bridge
+ * @np: device tree node containing panel bridge output ports
+ *
+ * Remove the panel bridge of a given DT node's port and endpoint number
+ *
+ * Returns zero if successful, or one of the standard error codes if it fails.
+ */
+int drm_of_panel_bridge_remove(const struct device_node *np,
+			       int port, int endpoint)
+{
+	struct drm_bridge *bridge;
+	struct device_node *remote;
+
+	remote = of_graph_get_remote_node(np, port, endpoint);
+	if (!remote)
+		return -ENODEV;
+
+	bridge = of_drm_find_bridge(remote);
+	drm_panel_bridge_remove(bridge);
+
+	return 0;
+}
+#else
+int drm_of_panel_bridge_remove(const struct device_node *np,
+			       int port, int endpoint)
+{
+	return -EINVAL;
+}
+#endif
+EXPORT_SYMBOL_GPL(drm_of_panel_bridge_remove);

include/drm/drm_of.h

@@ -29,6 +29,8 @@ int drm_of_find_panel_or_bridge(const struct device_node *np,
 				int port, int endpoint,
 				struct drm_panel **panel,
 				struct drm_bridge **bridge);
+int drm_of_panel_bridge_remove(const struct device_node *np,
+			       int port, int endpoint);
 #else
 static inline uint32_t drm_of_find_possible_crtcs(struct drm_device *dev,
 						  struct device_node *port)
@@ -65,6 +67,12 @@ static inline int drm_of_find_panel_or_bridge(const struct device_node *np,
 {
 	return -EINVAL;
 }
+
+static inline int drm_of_panel_bridge_remove(const struct device_node *np,
+					     int port, int endpoint)
+{
+	return -EINVAL;
+}
 #endif
 
 static inline int drm_of_encoder_active_endpoint_id(struct device_node *node,