linux-kernel - [PATCH 1/2] drm/bridge: Support finding bridge with struct device

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Date: Tue, 14 May 2024 23:40:44 +0800
From: Sui Jingfeng <sui.jingfeng@...ux.dev>
To: Neil Armstrong <neil.armstrong@...aro.org>,
	Maxime Ripard <mripard@...nel.org>,
	Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc: dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org,
	Sui Jingfeng <sui.jingfeng@...ux.dev>
Subject: [PATCH 1/2] drm/bridge: Support finding bridge with struct device

The pointer of 'struct device' can also be used as a key to search drm
bridge instance from the global bridge list, traditionally, fwnode and
'OF' based APIs requires the system has decent fwnode/OF Graph support.
While the drm_find_bridge_by_dev() function introduced in this series
don't has such a restriction. It only require you has a pointer to the
backing device. Hence, it may suitable for some small and/or limited
display subsystems.

Also add the drm_bridge_add_with_dev() as a helper, which automatically
set the .of_node field of drm_bridge instances if you call it. But it
suitable for simple bridge drivers which one device backing one drm_bridge
instance.

Signed-off-by: Sui Jingfeng <sui.jingfeng@...ux.dev>
---
 drivers/gpu/drm/drm_bridge.c | 39 ++++++++++++++++++++++++++++++++++++
 include/drm/drm_bridge.h     |  5 +++++
 2 files changed, 44 insertions(+)

diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 584d109330ab..1928d9d0dd3c 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -213,6 +213,23 @@ void drm_bridge_add(struct drm_bridge *bridge)
 }
 EXPORT_SYMBOL(drm_bridge_add);
 
+/**
+ * drm_bridge_add_with_dev - add the given bridge to the global bridge list
+ *
+ * @bridge: bridge control structure
+ * @dev: pointer to the kernel device that this bridge is backed.
+ */
+void drm_bridge_add_with_dev(struct drm_bridge *bridge, struct device *dev)
+{
+	if (dev) {
+		bridge->kdev = dev;
+		bridge->of_node = dev->of_node;
+	}
+
+	drm_bridge_add(bridge);
+}
+EXPORT_SYMBOL_GPL(drm_bridge_add_with_dev);
+
 static void drm_bridge_remove_void(void *bridge)
 {
 	drm_bridge_remove(bridge);
@@ -1334,6 +1351,27 @@ void drm_bridge_hpd_notify(struct drm_bridge *bridge,
 }
 EXPORT_SYMBOL_GPL(drm_bridge_hpd_notify);
 
+struct drm_bridge *drm_find_bridge_by_dev(struct device *kdev)
+{
+	struct drm_bridge *bridge;
+
+	if (!kdev)
+		return NULL;
+
+	mutex_lock(&bridge_lock);
+
+	list_for_each_entry(bridge, &bridge_list, list) {
+		if (bridge->kdev == kdev) {
+			mutex_unlock(&bridge_lock);
+			return bridge;
+		}
+	}
+
+	mutex_unlock(&bridge_lock);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(drm_find_bridge_by_dev);
+
 #ifdef CONFIG_OF
 /**
  * of_drm_find_bridge - find the bridge corresponding to the device node in
@@ -1361,6 +1399,7 @@ struct drm_bridge *of_drm_find_bridge(struct device_node *np)
 	return NULL;
 }
 EXPORT_SYMBOL(of_drm_find_bridge);
+
 #endif
 
 MODULE_AUTHOR("Ajay Kumar <ajaykumar.rs@...sung.com>");
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 4baca0d9107b..70d8393bbd9c 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -715,6 +715,8 @@ struct drm_bridge {
 	struct drm_private_obj base;
 	/** @dev: DRM device this bridge belongs to */
 	struct drm_device *dev;
+	/** @kdev: pointer to the kernel device backing this bridge */
+	struct device *kdev;
 	/** @encoder: encoder to which this bridge is connected */
 	struct drm_encoder *encoder;
 	/** @chain_node: used to form a bridge chain */
@@ -782,12 +784,15 @@ drm_priv_to_bridge(struct drm_private_obj *priv)
 }
 
 void drm_bridge_add(struct drm_bridge *bridge);
+void drm_bridge_add_with_dev(struct drm_bridge *bridge, struct device *dev);
 int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge);
 void drm_bridge_remove(struct drm_bridge *bridge);
 int drm_bridge_attach(struct drm_encoder *encoder, struct drm_bridge *bridge,
 		      struct drm_bridge *previous,
 		      enum drm_bridge_attach_flags flags);
 
+struct drm_bridge *drm_find_bridge_by_dev(struct device *kdev);
+
 #ifdef CONFIG_OF
 struct drm_bridge *of_drm_find_bridge(struct device_node *np);
 #else
-- 
2.43.0