From nobody Wed Oct 1 23:30:05 2025 Received: from smtpout-03.galae.net (smtpout-03.galae.net [185.246.85.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 15E8523506F for ; Fri, 26 Sep 2025 16:35:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.246.85.4 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758904511; cv=none; b=A37gICfKwubiqqUU12zrk4Zdx279GDk5pQbzPY8L9MMUi20pz/eI6s3bUx27g7ApQgV3nJdVr1vKvQQ+H5PiMnNNteM1i8Zky16gKg62FpGE+TD3jpsYWybPXQPurX0ZezJ4VXFrqc6HewxXXkp1bMxZ07EqyEbT85K+iPOMRW4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758904511; c=relaxed/simple; bh=Tjtf+qkmGfwEJxwpsS39gFlyPr9z1XY1oZupy2jZouE=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=g6DXrOdKBH+iRqxPNT5vyupT6S8arJGqCl2osTbL5gf7btOQrBmPZquNXUcfwVwMFEAiXD6+eL89HNx5Ow6JQGNzggMp0feRv1UtnOWMWZJ46n7++5OaYjWaAYDSZqtgTctjLDb9Fl9KPFYfZBzoDLY7aAL3dhqVtWwDM7T0pYU= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com; spf=pass smtp.mailfrom=bootlin.com; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b=UQc9EmEw; arc=none smtp.client-ip=185.246.85.4 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=bootlin.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=bootlin.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=bootlin.com header.i=@bootlin.com header.b="UQc9EmEw" Received: from smtpout-01.galae.net (smtpout-01.galae.net [212.83.139.233]) by smtpout-03.galae.net (Postfix) with ESMTPS id 686704E40E11; Fri, 26 Sep 2025 16:35:07 +0000 (UTC) Received: from mail.galae.net (mail.galae.net [212.83.136.155]) by smtpout-01.galae.net (Postfix) with ESMTPS id 3EBD9606B5; Fri, 26 Sep 2025 16:35:07 +0000 (UTC) Received: from [127.0.0.1] (localhost [127.0.0.1]) by localhost (Mailerdaemon) with ESMTPSA id 40313102F18CE; Fri, 26 Sep 2025 18:35:04 +0200 (CEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bootlin.com; s=dkim; t=1758904506; h=from:subject:date:message-id:to:cc:mime-version:content-type: content-transfer-encoding:in-reply-to:references; bh=6xVw/khtwiX9YEqRoJlZJqW1RWke6AJC8b2cUTe6EF4=; b=UQc9EmEwq8CeuvRpDVvNT+LRASjb0Nqr+P7f9zDqVMuUWvFi4hWxc1WDDzwGItwtZWJNdt TpFuTAAIbE+A5eO4BXnILDMzL5YC2H1dJUM6BEVk39vQ+gegdqm5HWRmCkr1o5X8J7q5+f kdq5fdMjbc/mQzZxLASB8sPjdXb9OhhSAsZ1+xOu54z3urts6qVMnfznsTEko9x9isPI8q 6TKsKDQLmdm77Tzdq4S41ryzJ4KCXKn2SPmR88UXMGCntvX7kateFedm4jNV6ihl1JLh+P tZB2VUFFqKMv2F5VqNWygXcCtwP/ReY+ZqmE37GBiXbmVvaheCAa3ncm+mR1Yg== From: Luca Ceresoli Date: Fri, 26 Sep 2025 18:33:27 +0200 Subject: [PATCH v2 1/2] drm/bridge: add drm_bridge_unplug() and drm_bridge_enter/exit() Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Message-Id: <20250926-drm-bridge-atomic-vs-remove-v2-1-69f7d5ca1a92@bootlin.com> References: <20250926-drm-bridge-atomic-vs-remove-v2-0-69f7d5ca1a92@bootlin.com> In-Reply-To: <20250926-drm-bridge-atomic-vs-remove-v2-0-69f7d5ca1a92@bootlin.com> To: Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter Cc: Hui Pu , Thomas Petazzoni , dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, Luca Ceresoli , Dmitry Baryshkov X-Mailer: b4 0.14.2 X-Last-TLS-Session-Version: TLSv1.3 To allow DRM bridges to be removable, add synchronization functions allowing to tell when a bridge hardware has been physically unplugged and to mark a critical section that should not be entered after that. This is inspired by the drm_dev_unplugged/enter/exit() functions for struct drm_device. Suggested-by: Maxime Ripard Link: https://lore.kernel.org/all/20250106-vigorous-talented-viper-fa49d9@h= ouat/ Signed-off-by: Luca Ceresoli --- drivers/gpu/drm/drm_bridge.c | 58 ++++++++++++++++++++++++++++++++++++++++= ++++ include/drm/drm_bridge.h | 12 +++++++++ 2 files changed, 70 insertions(+) diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c index d031447eebc955efcf1e018d39c015b62b969eae..3ebf6cc820e058a67f712763c34= 1a75c671c82d1 100644 --- a/drivers/gpu/drm/drm_bridge.c +++ b/drivers/gpu/drm/drm_bridge.c @@ -27,6 +27,7 @@ #include #include #include +#include =20 #include #include @@ -200,6 +201,63 @@ static DEFINE_MUTEX(bridge_lock); static LIST_HEAD(bridge_list); =20 +DEFINE_STATIC_SRCU(drm_bridge_unplug_srcu); + +/** + * drm_bridge_enter - Enter DRM bridge critical section + * @dev: DRM bridge + * @idx: Pointer to index that will be passed to the matching drm_bridge_e= xit() + * + * This function marks and protects the beginning of a section that should= not + * be entered after the bridge has been unplugged. The section end is mark= ed + * with drm_bridge_exit(). Calls to this function can be nested. + * + * Returns: + * True if it is OK to enter the section, false otherwise. + */ +bool drm_bridge_enter(struct drm_bridge *bridge, int *idx) +{ + *idx =3D srcu_read_lock(&drm_bridge_unplug_srcu); + + if (bridge->unplugged) { + srcu_read_unlock(&drm_bridge_unplug_srcu, *idx); + return false; + } + + return true; +} +EXPORT_SYMBOL(drm_bridge_enter); + +/** + * drm_bridge_exit - Exit DRM bridge critical section + * @idx: index returned by drm_bridge_enter() + * + * This function marks the end of a section that should not be entered aft= er + * the bridge has been unplugged. + */ +void drm_bridge_exit(int idx) +{ + srcu_read_unlock(&drm_bridge_unplug_srcu, idx); +} +EXPORT_SYMBOL(drm_bridge_exit); + +/** + * drm_bridge_unplug - unplug a DRM bridge + * @dev: DRM bridge + * + * This tells the bridge has been physically unplugged and no operations on + * device resources must be done anymore. Entry-points can use + * drm_bridge_enter() and drm_bridge_exit() to protect device resources in + * a race free manner. + */ +void drm_bridge_unplug(struct drm_bridge *bridge) +{ + bridge->unplugged =3D true; + + synchronize_srcu(&drm_bridge_unplug_srcu); +} +EXPORT_SYMBOL(drm_bridge_unplug); + static void __drm_bridge_free(struct kref *kref) { struct drm_bridge *bridge =3D container_of(kref, struct drm_bridge, refco= unt); diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h index 76e05930f50e00f6ef5999b3f5a476215951028d..6b325de9e41ba7ee3649eaa60df= e105d6155f824 100644 --- a/include/drm/drm_bridge.h +++ b/include/drm/drm_bridge.h @@ -1143,6 +1143,14 @@ struct drm_bridge { */ struct kref refcount; =20 + /** + * @unplugged: + * + * Flag to tell if the bridge has been unplugged. + * See drm_bridge_enter() and drm_bridge_unplug(). + */ + bool unplugged; + /** @driver_private: pointer to the bridge driver's internal context */ void *driver_private; /** @ops: bitmask of operations supported by the bridge */ @@ -1278,6 +1286,10 @@ drm_priv_to_bridge(struct drm_private_obj *priv) return container_of(priv, struct drm_bridge, base); } =20 +bool drm_bridge_enter(struct drm_bridge *bridge, int *idx); +void drm_bridge_exit(int idx); +void drm_bridge_unplug(struct drm_bridge *bridge); + struct drm_bridge *drm_bridge_get(struct drm_bridge *bridge); void drm_bridge_put(struct drm_bridge *bridge); =20 --=20 2.51.0