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Message-Id: <20240510-hotplug-drm-bridge-v2-2-ec32f2c66d56@bootlin.com>
Date: Fri, 10 May 2024 09:10:38 +0200
From: Luca Ceresoli <luca.ceresoli@...tlin.com>
To: Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
Conor Dooley <conor+dt@...nel.org>, 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>, Daniel Vetter <daniel@...ll.ch>,
Derek Kiernan <derek.kiernan@....com>,
Dragan Cvetic <dragan.cvetic@....com>, Arnd Bergmann <arnd@...db.de>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Saravana Kannan <saravanak@...gle.com>
Cc: Paul Kocialkowski <contact@...lk.fr>,
Hervé Codina <herve.codina@...tlin.com>,
Thomas Petazzoni <thomas.petazzoni@...tlin.com>, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
Paul Kocialkowski <paul.kocialkowski@...tlin.com>,
Luca Ceresoli <luca.ceresoli@...tlin.com>
Subject: [PATCH v2 2/5] drm/bridge: add bridge notifier to be notified of
bridge addition and removal
From: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
In preparation for allowing bridges to be added to and removed from a DRM
card without destroying the whole card, add a DRM bridge notifier. Notified
events are addition and removal to/from the global bridge list.
Co-developed-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@...tlin.com>
---
drivers/gpu/drm/drm_bridge.c | 35 +++++++++++++++++++++++++++++++++++
include/drm/drm_bridge.h | 19 +++++++++++++++++++
2 files changed, 54 insertions(+)
diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
index 521a71c61b16..245f7fa4ea22 100644
--- a/drivers/gpu/drm/drm_bridge.c
+++ b/drivers/gpu/drm/drm_bridge.c
@@ -25,6 +25,7 @@
#include <linux/media-bus-format.h>
#include <linux/module.h>
#include <linux/mutex.h>
+#include <linux/notifier.h>
#include <drm/drm_atomic_state_helper.h>
#include <drm/drm_bridge.h>
@@ -197,6 +198,36 @@
static DEFINE_MUTEX(bridge_lock);
static LIST_HEAD(bridge_list);
+static BLOCKING_NOTIFIER_HEAD(bridge_notifier);
+
+/**
+ * drm_bridge_notifier_register - add a DRM bridge notifier
+ * @nb: the notifier block to be registered
+ *
+ * The notifier block will be notified of events defined in
+ * &drm_bridge_notifier_event
+ */
+int drm_bridge_notifier_register(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_register(&bridge_notifier, nb);
+}
+EXPORT_SYMBOL(drm_bridge_notifier_register);
+
+/**
+ * drm_bridge_notifier_unregister - remove a DRM bridge notifier
+ * @nb: the notifier block to be unregistered
+ */
+int drm_bridge_notifier_unregister(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_unregister(&bridge_notifier, nb);
+}
+EXPORT_SYMBOL(drm_bridge_notifier_unregister);
+
+static void drm_bridge_notifier_notify(unsigned long event,
+ struct drm_bridge *bridge)
+{
+ blocking_notifier_call_chain(&bridge_notifier, event, bridge);
+}
/**
* drm_bridge_add - add the given bridge to the global bridge list
@@ -210,6 +241,8 @@ void drm_bridge_add(struct drm_bridge *bridge)
mutex_lock(&bridge_lock);
list_add_tail(&bridge->list, &bridge_list);
mutex_unlock(&bridge_lock);
+
+ drm_bridge_notifier_notify(DRM_BRIDGE_NOTIFY_ADD, bridge);
}
EXPORT_SYMBOL(drm_bridge_add);
@@ -243,6 +276,8 @@ EXPORT_SYMBOL(devm_drm_bridge_add);
*/
void drm_bridge_remove(struct drm_bridge *bridge)
{
+ drm_bridge_notifier_notify(DRM_BRIDGE_NOTIFY_REMOVE, bridge);
+
mutex_lock(&bridge_lock);
list_del_init(&bridge->list);
mutex_unlock(&bridge_lock);
diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
index 4baca0d9107b..ee48c1eb76ae 100644
--- a/include/drm/drm_bridge.h
+++ b/include/drm/drm_bridge.h
@@ -43,6 +43,22 @@ struct drm_panel;
struct edid;
struct i2c_adapter;
+/**
+ * enum drm_bridge_notifier_event - DRM bridge events
+ */
+enum drm_bridge_notifier_event {
+ /**
+ * @DRM_BRIDGE_NOTIFY_ADD: A bridge has just been added to the
+ * global bridge list. See drm_bridge_add().
+ */
+ DRM_BRIDGE_NOTIFY_ADD,
+ /**
+ * @DRM_BRIDGE_NOTIFY_REMOVE: A bridge is about to be removed from
+ * the global bridge list. See drm_bridge_remove().
+ */
+ DRM_BRIDGE_NOTIFY_REMOVE,
+};
+
/**
* enum drm_bridge_attach_flags - Flags for &drm_bridge_funcs.attach
*/
@@ -781,6 +797,9 @@ drm_priv_to_bridge(struct drm_private_obj *priv)
return container_of(priv, struct drm_bridge, base);
}
+int drm_bridge_notifier_register(struct notifier_block *nb);
+int drm_bridge_notifier_unregister(struct notifier_block *nb);
+
void drm_bridge_add(struct drm_bridge *bridge);
int devm_drm_bridge_add(struct device *dev, struct drm_bridge *bridge);
void drm_bridge_remove(struct drm_bridge *bridge);
--
2.34.1
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