linux-kernel - [PATCH v6 17/26] drm/bridge: add devm_drm_put_bridge() and devm_drm_put_and_clear

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Message-Id: <20250206-hotplug-drm-bridge-v6-17-9d6f2c9c3058@bootlin.com>
Date: Thu, 06 Feb 2025 19:14:32 +0100
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Simona Vetter <simona@...ll.ch>, Inki Dae <inki.dae@...sung.com>, 
 Jagan Teki <jagan@...rulasolutions.com>, 
 Marek Szyprowski <m.szyprowski@...sung.com>, 
 Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
 Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, 
 Pengutronix Kernel Team <kernel@...gutronix.de>, 
 Fabio Estevam <festevam@...il.com>, Daniel Thompson <danielt@...nel.org>, 
 Andrzej Hajda <andrzej.hajda@...el.com>, Jonathan Corbet <corbet@....net>, 
 Sam Ravnborg <sam@...nborg.org>, Boris Brezillon <bbrezillon@...nel.org>, 
 Nicolas Ferre <nicolas.ferre@...rochip.com>, 
 Alexandre Belloni <alexandre.belloni@...tlin.com>, 
 Claudiu Beznea <claudiu.beznea@...on.dev>, 
 Jessica Zhang <quic_jesszhan@...cinc.com>
Cc: Paul Kocialkowski <contact@...lk.fr>, 
 Maxime Ripard <mripard@...nel.org>, 
 Dmitry Baryshkov <dmitry.baryshkov@...aro.org>, 
 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>, 
 Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
 Hervé Codina <herve.codina@...tlin.com>, 
 Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
 linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
 linux-doc@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, 
 Paul Kocialkowski <paul.kocialkowski@...tlin.com>, 
 Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH v6 17/26] drm/bridge: add devm_drm_put_bridge() and
 devm_drm_put_and_clear_bridge()

Bridges obtained via devm_drm_of_get_bridge() will be put when the
requesting device is removed. However drivers which obtained them may need
to put the obtained reference way before being destroyed, especially in
case of hot-unplug of the bridge they hold a reference to.

Add devm_drm_put_bridge() to manually release a devm-obtained bridge.

Also add a macro to additionally clear the pointer in a safe way.

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

---

This patch was added in v6.
---
 drivers/gpu/drm/drm_bridge.c | 36 ++++++++++++++++++++++++++++++++++++
 include/drm/drm_bridge.h     |  6 ++++++
 2 files changed, 42 insertions(+)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index fca860d582f86b35c9172b27be20060de086e38f..92ce40adfaa59a278a972ac862bebee06970ff83 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -1548,6 +1548,42 @@ struct drm_bridge *devm_drm_of_get_bridge_by_node(struct device *dev,
 }
 EXPORT_SYMBOL(devm_drm_of_get_bridge_by_node);
 
+/**
+ * devm_drm_put_bridge - Release a bridge reference obtained via devm
+ * @dev: device that got the bridge via devm
+ * @bridge: pointer to a struct drm_bridge obtained via devm
+ *
+ * Same as drm_bridge_put() for bridge pointers obtained via devm functions
+ * such as devm_drm_of_get_bridge().
+ *
+ * See also devm_drm_put_and_clear_bridge() which is more handy in many
+ * cases.
+ */
+void devm_drm_put_bridge(struct device *dev, struct drm_bridge *bridge)
+{
+	devm_release_action(dev, devm_drm_bridge_put_void, bridge);
+}
+EXPORT_SYMBOL(devm_drm_put_bridge);
+
+/**
+ * devm_drm_put_and_clear_bridge - Given a bridge pointer obained via devm,
+ *                                 clear the pointer then put the bridge
+ *
+ * @dev: device that got the bridge via devm
+ * @bridge_pp: pointer to pointer to a struct drm_bridge obtained via devm
+ *
+ * Same as drm_bridge_put_and_clear() for bridge pointers obtained via devm
+ * functions such as devm_drm_of_get_bridge().
+ */
+void devm_drm_put_and_clear_bridge(struct device *dev, struct drm_bridge **bridge_pp)
+{
+	struct drm_bridge *bridge = *bridge_pp;
+
+	*bridge_pp = NULL;
+	devm_drm_put_bridge(dev, bridge);
+}
+EXPORT_SYMBOL(devm_drm_put_and_clear_bridge);
+
 static void drmm_bridge_put_void(struct drm_device *drm, void *ptr)
 {
 	struct drm_bridge *bridge = ptr;
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 43cef0f6ccd36034f64ad2babfebea62db1d9e43..b6b76161a3c6bb2a4df4b3331bc152a560823fd7 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1230,6 +1230,8 @@ struct drm_bridge *devm_drm_of_get_bridge(struct device *dev, struct device_node
 					  u32 port, u32 endpoint);
 struct drm_bridge *devm_drm_of_get_bridge_by_node(struct device *dev,
 						  struct device_node *bridge_node);
+void devm_drm_put_bridge(struct device *dev, struct drm_bridge *bridge);
+void devm_drm_put_and_clear_bridge(struct device *dev, struct drm_bridge **bridge_pp);
 struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm, struct device_node *node,
 					  u32 port, u32 endpoint);
 #else
@@ -1247,6 +1249,10 @@ static inline struct drm_bridge *devm_drm_of_get_bridge_by_node(struct device *d
 	return ERR_PTR(-ENODEV);
 }
 
+static inline void devm_drm_put_bridge(struct device *dev, struct drm_bridge *bridge) {}
+static inline void devm_drm_put_and_clear_bridge(struct device *dev,
+						 struct drm_bridge **bridge_pp) {}
+
 static inline struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm,
 						     struct device_node *node,
 						     u32 port,

-- 
2.34.1