linux-kernel - Re: [PATCH v8 2/3] dmr/bridge: add a .destroy func

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Message-ID: <20250522-hot-hopeful-smilodon-dfb5b6@houat>
Date: Thu, 22 May 2025 17:43:37 +0200
From: Maxime Ripard <mripard@...nel.org>
To: Luca Ceresoli <luca.ceresoli@...tlin.com>
Cc: Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, 
	Simona Vetter <simona@...ll.ch>, 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>, Anusha Srivatsa <asrivats@...hat.com>, 
	Paul Kocialkowski <paulk@...-base.io>, Dmitry Baryshkov <lumag@...nel.org>, 
	Hervé Codina <herve.codina@...tlin.com>, Hui Pu <Hui.Pu@...ealthcare.com>, 
	Thomas Petazzoni <thomas.petazzoni@...tlin.com>, dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v8 2/3] dmr/bridge: add a .destroy func

On Fri, May 16, 2025 at 06:48:38PM +0200, Luca Ceresoli wrote:
> Some users of DRM bridges may need to execute specific code just before
> deallocation.
> 
> As of now the only known user would be KUnit tests.
> 
> Suggested-by: Maxime Ripard <mripard@...nel.org>
> Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
> 
> ---
> 
> This patch is new in v8. The .destroy callback had appeared in v5 as well
> [5], but as part of a larger patch and for different reason that do not
> apply anymore.
> 
> [5] https://lore.kernel.org/all/20241231-hotplug-drm-bridge-v5-3-173065a1ece1@bootlin.com/#t
> ---
>  drivers/gpu/drm/drm_bridge.c |  2 ++
>  include/drm/drm_bridge.h     | 10 ++++++++++
>  2 files changed, 12 insertions(+)
> 
> diff --git a/drivers/gpu/drm/drm_bridge.c b/drivers/gpu/drm/drm_bridge.c
> index b4c89ec01998b849018ce031c7cd84614e65e710..6185cb29fe3162264f0912c09c205fb467975dee 100644
> --- a/drivers/gpu/drm/drm_bridge.c
> +++ b/drivers/gpu/drm/drm_bridge.c
> @@ -203,6 +203,8 @@ static void __drm_bridge_free(struct kref *kref)
>  {
>  	struct drm_bridge *bridge = container_of(kref, struct drm_bridge, refcount);
>  
> +	if (bridge->funcs->destroy)
> +		bridge->funcs->destroy(bridge);
>  	kfree(bridge->container);
>  }
>  
> diff --git a/include/drm/drm_bridge.h b/include/drm/drm_bridge.h
> index 4e418a29a9ff9d014d6ac0910a5d9bcf7118195e..3ccd493faa580845c2ed1166f398eca27b464261 100644
> --- a/include/drm/drm_bridge.h
> +++ b/include/drm/drm_bridge.h
> @@ -86,6 +86,16 @@ struct drm_bridge_funcs {
>  	 */
>  	void (*detach)(struct drm_bridge *bridge);
>  
> +	/**
> +	 * @destroy:
> +	 *
> +	 * This callback is invoked when the bridge is about to be
> +	 * deallocated.
> +	 *
> +	 * The @destroy callback is optional.
> +	 */
> +	void (*destroy)(struct drm_bridge *bridge);
> +

destroy is before detach in alphabetical order, but otherwise it looks
good to me.

Once fixed,
Acked-by: Maxime Ripard <mripard@...nel.org>

Maxime

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