[PATCH v3 20/22] drm/bridge: add devm_drm_put_bridge()

[Luca Ceresoli <luca.ceresoli@bootlin.com>]

Bridges obtained via devm_drm_bridge_alloc(dev, ...) will be put when the
requesting device (@dev) is removed.

However drivers which obtained them may need to put the obtained reference
explicitly. One such case is if they bind the devm removal action to a
different device than the one implemented by the driver itself and which
might be removed at a different time, such as bridge/panel.c.

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

This function is considered only a temporary workaround until the panel
bridge is reworked and should be removed afterwards.

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

---

Changes in v3:
- document this function is a temporary workaround, not to be used
  (in kerneldoc and commit message)

Changes in v2: none
---
 drivers/gpu/drm/drm_bridge.c | 17 +++++++++++++++++
 include/drm/drm_bridge.h     |  4 ++++
 2 files changed, 21 insertions(+)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index b4c89ec01998b849018ce031c7cd84614e65e710..d0e81639927a73422671b7b43f3e8a946f1d4300 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -1392,6 +1392,23 @@ struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 EXPORT_SYMBOL(of_drm_find_bridge);
 #endif
 
+/**
+ * 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_bridge_alloc().
+ *
+ * This function is a temporary workaround and MUST NOT be used. Manual
+ * handling of bridge lifetime is inherently unsafe.
+ */
+void devm_drm_put_bridge(struct device *dev, struct drm_bridge *bridge)
+{
+	devm_release_action(dev, drm_bridge_put_void, bridge);
+}
+EXPORT_SYMBOL(devm_drm_put_bridge);
+
 static void drm_bridge_debugfs_show_bridge(struct drm_printer *p,
 					   struct drm_bridge *bridge,
 					   unsigned int idx)
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 4e418a29a9ff9d014d6ac0910a5d9bcf7118195e..6f00a3998ed6d026332b0f1e3bb5bee3cb5158e0 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -1265,6 +1265,8 @@ static inline struct drm_bridge *devm_drm_of_get_bridge(struct device *dev,
 	return ERR_PTR(-ENODEV);
 }
 
+static inline void devm_drm_put_bridge(struct device *dev, struct drm_bridge *bridge) {}
+
 static inline struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm,
 						     struct device_node *node,
 						     u32 port,
@@ -1274,6 +1276,8 @@ static inline struct drm_bridge *drmm_of_get_bridge(struct drm_device *drm,
 }
 #endif
 
+void devm_drm_put_bridge(struct device *dev, struct drm_bridge *bridge);
+
 void drm_bridge_debugfs_params(struct dentry *root);
 void drm_bridge_debugfs_encoder_params(struct dentry *root, struct drm_encoder *encoder);
 

-- 
2.49.0