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

["Luca Ceresoli" <luca.ceresoli@bootlin.com>]

Hello Linus,

On Mon Jan 19, 2026 at 9:54 AM CET, Linus Walleij wrote:
> On Fri, Jan 16, 2026 at 6:33 PM Luca Ceresoli <luca.ceresoli@bootlin.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@bootlin.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.

Thanks for sharing these info! I'm very happy to know I can break instead
of warning here. Change queued for v2.

Luca

--
Luca Ceresoli, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com