drm/bridge: Move devm_drm_of_get_bridge to bridge/panel.c

By depending on devm_drm_panel_bridge_add(), devm_drm_of_get_bridge()
introduces a circular dependency between the modules drm (where
devm_drm_of_get_bridge() ends up) and drm_kms_helper (where
devm_drm_panel_bridge_add() is).

Fix this by moving devm_drm_of_get_bridge() to bridge/panel.c and thus
drm_kms_helper.

Fixes: 87ea9580 ("drm/bridge: Add a function to abstract away panels")
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Maxime Ripard <maxime@cerno.tech>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Link: https://patchwork.freedesktop.org/patch/msgid/20210917180925.2602266-1-maxime@cerno.tech

drivers/gpu/drm/bridge/panel.c

@@ -9,6 +9,7 @@
 #include <drm/drm_connector.h>
 #include <drm/drm_encoder.h>
 #include <drm/drm_modeset_helper_vtables.h>
+#include <drm/drm_of.h>
 #include <drm/drm_panel.h>
 #include <drm/drm_print.h>
 #include <drm/drm_probe_helper.h>
@@ -332,3 +333,39 @@ struct drm_connector *drm_panel_bridge_connector(struct drm_bridge *bridge)
 	return &panel_bridge->connector;
 }
 EXPORT_SYMBOL(drm_panel_bridge_connector);
+
+#ifdef CONFIG_OF
+/**
+ * devm_drm_of_get_bridge - Return next bridge in the chain
+ * @dev: device to tie the bridge lifetime to
+ * @np: device tree node containing encoder output ports
+ * @port: port in the device tree node
+ * @endpoint: endpoint in the device tree node
+ *
+ * Given a DT node's port and endpoint number, finds the connected node
+ * and returns the associated bridge if any, or creates and returns a
+ * drm panel bridge instance if a panel is connected.
+ *
+ * Returns a pointer to the bridge if successful, or an error pointer
+ * otherwise.
+ */
+struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
+					  struct device_node *np,
+					  u32 port, u32 endpoint)
+{
+	struct drm_bridge *bridge;
+	struct drm_panel *panel;
+	int ret;
+
+	ret = drm_of_find_panel_or_bridge(np, port, endpoint,
+					  &panel, &bridge);
+	if (ret)
+		return ERR_PTR(ret);
+
+	if (panel)
+		bridge = devm_drm_panel_bridge_add(dev, panel);
+
+	return bridge;
+}
+EXPORT_SYMBOL(devm_drm_of_get_bridge);
+#endif

drivers/gpu/drm/drm_bridge.c

@@ -1232,40 +1232,6 @@ struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 	return NULL;
 }
 EXPORT_SYMBOL(of_drm_find_bridge);
-
-/**
- * devm_drm_of_get_bridge - Return next bridge in the chain
- * @dev: device to tie the bridge lifetime to
- * @np: device tree node containing encoder output ports
- * @port: port in the device tree node
- * @endpoint: endpoint in the device tree node
- *
- * Given a DT node's port and endpoint number, finds the connected node
- * and returns the associated bridge if any, or creates and returns a
- * drm panel bridge instance if a panel is connected.
- *
- * Returns a pointer to the bridge if successful, or an error pointer
- * otherwise.
- */
-struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
-					  struct device_node *np,
-					  u32 port, u32 endpoint)
-{
-	struct drm_bridge *bridge;
-	struct drm_panel *panel;
-	int ret;
-
-	ret = drm_of_find_panel_or_bridge(np, port, endpoint,
-					  &panel, &bridge);
-	if (ret)
-		return ERR_PTR(ret);
-
-	if (panel)
-		bridge = devm_drm_panel_bridge_add(dev, panel);
-
-	return bridge;
-}
-EXPORT_SYMBOL(devm_drm_of_get_bridge);
 #endif
 
 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@samsung.com>");