[PATCH] drm/gem: Check for valid formats

[Maíra Canal]

On 1/5/23 15:36, Simon Ser wrote:
> On Thursday, January 5th, 2023 at 19:30, Maíra Canal <mcanal at igalia.com> wrote:
> 
>>>>> I think to really make sure we have consensus it'd be good to extend this
>>>>> to a series which removes all the callers to drm_any_plane_has_format()
>>>>> from the various drivers, and then unexports that helper. That way your
>>>>> series here will have more eyes on it :-)
>>>>
>>>> I took a look at the callers to drm_any_plane_has_format() and there are only
>>>> 3 callers (amdgpu, i915 and vmwgfx). They all use drm_any_plane_has_format()
>>>> before calling drm_framebuffer_init(). So, I'm not sure I could remove
>>>> drm_any_plane_has_format() from those drivers. Maybe adding this same check
>>>> to drm_gem_fb_init() and refactor the drivers to make them use drm_gem_fb_init(),
>>>> but I guess this would be part of a different series.
>>>
>>> Well vmwgfx still not yet using gem afaik, so that doesn't work.
>>>
>>> But why can't we move the modifier check int drm_framebuffer_init()?
>>> That's kinda where it probably should be anyway, there's nothing gem
>>> bo specific in the code you're adding.
>>
>>
>> I'm not sure if this would correct the problem that I was trying to fix initially.
>> I was trying to make sure that the drivers pass on the
>> igt at kms_addfb_basic@addfb25-bad-modifier IGT test by making sure that the addfb
>> ioctl returns the error.
>>
>> By moving the modifier check to the drm_framebuffer_init(), the test would still
>> fail.
> 
> Hm, why is that? The ADDFB2 IOCTL impl calls drm_framebuffer_init().

 From what I can see, ADDFB2 IOCTL calls drm_internal_framebuffer_create() [1],
then drm_internal_framebuffer_create() calls the fb_create hook [2]. I'm not sure
here ADDFB2 implicitly calls drm_framebuffer_init(), but I'm probably missing
something.

Also, by looking at this file, I realize that maybe it would be better to add the
check on framebuffer_check(), but I don't know how does it sound to Daniel.

[1] https://cgit.freedesktop.org/drm/drm-misc/tree/drivers/gpu/drm/drm_framebuffer.c#n346
[2] https://cgit.freedesktop.org/drm/drm-misc/tree/drivers/gpu/drm/drm_framebuffer.c#n321

Best Regards,
- Maíra Canal