linux-kernel - Re: [PATCH 3/6] drm/mcde: dsi: warn in case of multiple subnodes

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAD++jLm_Va+7c_usgoPDhsDiCr4NQMZWsQ3iJW5-a1ETP4EaJQ@mail.gmail.com>
Date: Mon, 19 Jan 2026 09:54:30 +0100
From: Linus Walleij <linusw@...nel.org>
To: Luca Ceresoli <luca.ceresoli@...tlin.com>
Cc: Biju Das <biju.das.jz@...renesas.com>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>, 
	Anitha Chrisanthus <anitha.chrisanthus@...el.com>, Edmund Dea <edmund.j.dea@...el.com>, 
	Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>, 
	Tomi Valkeinen <tomi.valkeinen+renesas@...asonboard.com>, 
	Kieran Bingham <kieran.bingham+renesas@...asonboard.com>, 
	Geert Uytterhoeven <geert+renesas@...der.be>, Magnus Damm <magnus.damm@...il.com>, 
	Tomi Valkeinen <tomi.valkeinen@...asonboard.com>, Hui Pu <Hui.Pu@...ealthcare.com>, 
	Ian Ray <ian.ray@...ealthcare.com>, Thomas Petazzoni <thomas.petazzoni@...tlin.com>, 
	dri-devel@...ts.freedesktop.org, linux-renesas-soc@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/6] drm/mcde: dsi: warn in case of multiple subnodes

On Fri, Jan 16, 2026 at 6:33 PM Luca Ceresoli <luca.ceresoli@...tlin.com> wrote:

> mcde_dsi_bind() has a loop over all subnodes looking for a panel, but does
> not exit when a match is found and only stores the last match. However this
> will be problematic when introducing refcounting on the struct drm_device
> pointer in a following commit, because of_drm_find_and_get_bridge() would
> get a reference to multiple bridges.
>
> Assuming there is no real reason for looking for multiple panels, add a
> warning so it gets noticed in case the assumption is wrong.
>
> Signed-off-by: Luca Ceresoli <luca.ceresoli@...tlin.com>
>
> ---
>
> I think the correct thing to do would be adding a break statement when
> there is a match. However I don't have knowledge of this driver and the
> hardware, thus this patch is a prudential alternative, not changing the
> behaviour.

Go ahead and insert a break when the panel is found, there is
no MCDE-attached device with more than one panel.

There *exist* the Samsung Gavini device which has a
LED panel, *and* the same lines attached to a mini-projector
so these two can be used at the same time. I have no idea
how to actually deal with that if someone one day want to
support it. Probably by putting the projector as a side thing
and not deal with the video stream in the device tree.

Yours,
Linus Walleij