linux-kernel - [PATCH v3 04/22] drm/bridge: make of_drm_find_bridge() a wrapper of of_drm_find_and_get

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Message-Id: <20251216-drm-bridge-alloc-getput-drm_of_find_bridge-v3-4-b5165fab8058@bootlin.com>
Date: Tue, 16 Dec 2025 18:58:37 +0100
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>, 
 Jonathan Corbet <corbet@....net>, Alexey Brodkin <abrodkin@...opsys.com>, 
 Phong LE <ple@...libre.com>, 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>, Kevin Hilman <khilman@...libre.com>, 
 Jerome Brunet <jbrunet@...libre.com>, 
 Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc: Hui Pu <Hui.Pu@...ealthcare.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org, 
 linux-doc@...r.kernel.org, imx@...ts.linux.dev, 
 linux-arm-kernel@...ts.infradead.org, linux-amlogic@...ts.infradead.org, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH v3 04/22] drm/bridge: make of_drm_find_bridge() a wrapper
 of of_drm_find_and_get_bridge()

of_drm_find_bridge() is identical to of_drm_find_and_get_bridge() except it
does not increment the refcount. Rewrite it as a wrapper and put the bridge
being returned so the behaviour is still the same.

Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>

---

Changes in v3:
- update after of_drm_get_bridge() -> of_drm_find_and_get_bridge() rename
- fixed kerneldoc syntax for non-kerneldoc comment

Changes in v2:
- Added comment to document why we put the reference
---
 drivers/gpu/drm/drm_bridge.c | 20 +++++++++-----------
 1 file changed, 9 insertions(+), 11 deletions(-)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index f612d486cad0..64aa69dcf46f 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -1529,19 +1529,17 @@ EXPORT_SYMBOL(of_drm_find_and_get_bridge);
  */
 struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 {
-	struct drm_bridge *bridge;
-
-	mutex_lock(&bridge_lock);
+	struct drm_bridge *bridge = of_drm_find_and_get_bridge(np);
 
-	list_for_each_entry(bridge, &bridge_list, list) {
-		if (bridge->of_node == np) {
-			mutex_unlock(&bridge_lock);
-			return bridge;
-		}
-	}
+	/*
+	 * We need to emulate the original semantics of
+	 * of_drm_find_bridge(), which was not getting any bridge
+	 * reference. Being now based on of_drm_find_and_get_bridge() which
+	 * gets a reference, put it before returning.
+	 */
+	drm_bridge_put(bridge);
 
-	mutex_unlock(&bridge_lock);
-	return NULL;
+	return bridge;
 }
 EXPORT_SYMBOL(of_drm_find_bridge);
 #endif

-- 
2.52.0