linux-kernel - [PATCH 7/9] drm/bridge: get the bridge returned by drm_bridge_get_next

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Message-Id: <20250709-drm-bridge-alloc-getput-drm_bridge_get_next_bridge-v1-7-48920b9cf369@bootlin.com>
Date: Wed, 09 Jul 2025 18:48:06 +0200
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Andrzej Hajda <andrzej.hajda@...el.com>, 
 Neil Armstrong <neil.armstrong@...aro.org>, Robert Foss <rfoss@...nel.org>, 
 Laurent Pinchart <Laurent.pinchart@...asonboard.com>, 
 Jonas Karlman <jonas@...boo.se>, Jernej Skrabec <jernej.skrabec@...il.com>, 
 Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
 Maxime Ripard <mripard@...nel.org>, Thomas Zimmermann <tzimmermann@...e.de>, 
 David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
 Liu Ying <victor.liu@....com>, Shawn Guo <shawnguo@...nel.org>, 
 Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, 
 Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, 
 Philipp Zabel <p.zabel@...gutronix.de>
Cc: Hui Pu <Hui.Pu@...ealthcare.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
 imx@...ts.linux.dev, linux-arm-kernel@...ts.infradead.org, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH 7/9] drm/bridge: get the bridge returned by
 drm_bridge_get_next_bridge()

drm_bridge_get_next_bridge() returns a bridge pointer that the
caller could hold for a long time. Increment the refcount of the returned
bridge and document it must be put by the caller.

Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
---
 include/drm/drm_bridge.h | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index c2a7a7d2dfc420e9dcf7ea4c093ce1f1b939c820..158d22892bf3ddb469d510735818f14a1c23d7a1 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1305,6 +1305,13 @@ drm_bridge_get_current_state(struct drm_bridge *bridge)
  * drm_bridge_get_next_bridge() - Get the next bridge in the chain
  * @bridge: bridge object
  *
+ * The caller is responsible of having a reference to @bridge via
+ * drm_bridge_get() or equivalent. This function leaves the refcount of
+ * @bridge unmodified.
+ *
+ * The refcount of the returned bridge is incremented. Use drm_bridge_put()
+ * when done with it.
+ *
  * RETURNS:
  * the next bridge in the chain after @bridge, or NULL if @bridge is the last.
  */
@@ -1314,7 +1321,7 @@ drm_bridge_get_next_bridge(struct drm_bridge *bridge)
 	if (list_is_last(&bridge->chain_node, &bridge->encoder->bridge_chain))
 		return NULL;
 
-	return list_next_entry(bridge, chain_node);
+	return drm_bridge_get(list_next_entry(bridge, chain_node));
 }
 
 /**

-- 
2.50.0