Re: [PATCH] drm/gem: Check for valid formats

From: Rob Clark <robdclark@gmail.com>
To: "Maíra Canal" <mcanal@igalia.com>
Cc: "Rob Clark" <robdclark@chromium.org>,
	"André Almeida" <andrealmeid@igalia.com>,
	"Thomas Zimmermann" <tzimmermann@suse.de>,
	"Melissa Wen" <mwen@igalia.com>,
	dri-devel@lists.freedesktop.org
Subject: Re: [PATCH] drm/gem: Check for valid formats
Date: Tue, 3 Jan 2023 18:22:01 -0800	[thread overview]
Message-ID: <CAF6AEGs+GP2MCbD=wW+ords=MPFBcV4ncag-5KBfO=2KWg3G0Q@mail.gmail.com> (raw)
In-Reply-To: <8d5deb15-e412-180f-585d-f57d193ae658@igalia.com>

On Tue, Jan 3, 2023 at 5:11 PM Maíra Canal <mcanal@igalia.com> wrote:
>
> On 1/3/23 19:46, Rob Clark wrote:
> > drive-by thought/concern, what are the odds that there is some wayland
> > compositor out there that creates an fb for every window surface, even
> > if it later decides to composite on the GPU because the display does
> > not support the format?  It seems like there is a non-zero chance of
> > breaking userspace..
> >
>
> As Simon pointed out, drivers like i915 and AMDGPU already reject IOCTLs
> with invalid parameters, as you can see on [1] and [2], so this patch
> would make the behavior more consistent between the drivers. That said,
> I don't believe that this patch would break userspace, as userspace
> already needs to handle with the existing drivers.

ok, maybe this won't be a problem then

BR,
-R

> [1] https://cgit.freedesktop.org/drm/drm-misc/tree/drivers/gpu/drm/i915/display/intel_fb.c#n1917
> [2] https://cgit.freedesktop.org/drm/drm-misc/tree/drivers/gpu/drm/amd/amdgpu/amdgpu_display.c#n1124
>
> Best Regards,
> - Maíra Canal
>
> > BR,
> > -R
> >
>