drm/bridge: drm_bridge_get/put(): document NULL pointer behaviour

drm_bridge_get and drm_bridge_put() do nothing when they are passed a NULL
pointer, and they do so since their initial addition in commit 30d1b37d4c02
("drm/bridge: add support for refcounting").

This allows simpler code in various places when using these
functions. However it's not documented, so it's not clear whether it is
part of the API "contract" or just a current implementation detail that
might change in the future.

There is no visible reason to remove this NULL check, so document it,
making it part of the contract, letting users count on it.

Reviewed-by: Liu Ying <victor.liu@nxp.com>
Reviewed-by: Louis Chauvet <louis.chauvet@bootlin.com>
Link: https://patch.msgid.link/20260324-drm-bridge-alloc-getput-document-null-check-v1-1-fb0877c49d7e@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 d6f512b733896d21d7330442a0375222c2113155..ba80bebb5685693517cadf7633679228b87c6b1c 100644 (file)
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -282,7 +282,7 @@ static void __drm_bridge_free(struct kref *kref)
 
 /**
  * drm_bridge_get - Acquire a bridge reference
- * @bridge: DRM bridge
+ * @bridge: DRM bridge; if NULL this function does nothing
  *
  * This function increments the bridge's refcount.
  *
@@ -300,7 +300,7 @@ EXPORT_SYMBOL(drm_bridge_get);
 
 /**
  * drm_bridge_put - Release a bridge reference
- * @bridge: DRM bridge
+ * @bridge: DRM bridge; if NULL this function does nothing
  *
  * This function decrements the bridge's reference count and frees the
  * object if the reference count drops to zero.