drm/bridge: add of_drm_find_and_get_bridge()

of_drm_find_bridge() does not increment the refcount for the returned
bridge, but that is required now. However converting it and all its users
is not realistically doable at once given the large amount of (direct and
indirect) callers and the complexity of some.

Solve this issue by creating a new of_drm_find_and_get_bridge() function
that is identical to of_drm_find_bridge() except also it takes a
reference. Then of_drm_find_bridge() will be deprecated to be eventually
removed.

Suggested-by: Maxime Ripard <mripard@kernel.org>
Link: https://lore.kernel.org/dri-devel/20250319-stylish-lime-mongoose-0a18ad@houat/
Reviewed-by: Maxime Ripard <mripard@kernel.org>
Link: https://patch.msgid.link/20251216-drm-bridge-alloc-getput-drm_of_find_bridge-v3-1-b5165fab8058@bootlin.com
Signed-off-by: Luca Ceresoli <luca.ceresoli@bootlin.com>

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index db40c26d1cb354f818f12a5a53f9baa6a7fc3574..0dbc8b59c3be04a49fb05db029802f6467e50595 100644 (file)
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -1479,6 +1479,31 @@ void drm_bridge_hpd_notify(struct drm_bridge *bridge,
 EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
 
 #ifdef CONFIG_OF
+/**
+ * of_drm_find_and_get_bridge - find the bridge corresponding to the device
+ *                              node in the global bridge list
+ * @np: device node
+ *
+ * The refcount of the returned bridge is incremented. Use drm_bridge_put()
+ * when done with it.
+ *
+ * RETURNS:
+ * drm_bridge control struct on success, NULL on failure
+ */
+struct drm_bridge *of_drm_find_and_get_bridge(struct device_node *np)
+{
+       struct drm_bridge *bridge;
+
+       scoped_guard(mutex, &bridge_lock) {
+               list_for_each_entry(bridge, &bridge_list, list)
+                       if (bridge->of_node == np)
+                               return drm_bridge_get(bridge);
+       }
+
+       return NULL;
+}
+EXPORT_SYMBOL(of_drm_find_and_get_bridge);
+
 /**
  * of_drm_find_bridge - find the bridge corresponding to the device node in
  *                     the global bridge list

diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 68b9da1eb5425d9aa9e2fd9ac9cf78cdc881c98a..42ec33116d188b7c5896394d24f7b551f6e64cf4 100644 (file)
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1326,8 +1326,13 @@ int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
                      enum drm_bridge_attach_flags flags);
 
 #ifdef CONFIG_OF
+struct drm_bridge *of_drm_find_and_get_bridge(struct device_node *np);
 struct drm_bridge *of_drm_find_bridge(struct device_node *np);
 #else
+static inline struct drm_bridge *of_drm_find_and_get_bridge(struct device_node *np)
+{
+       return NULL;
+}
 static inline struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 {
        return NULL;