[Mesa-dev] [PATCH 2/2] egl/drm: set the VISUAL_TYPE alongside the VISUAL_ID

[Daniel Stone]

Hi Emil,

On 21 August 2017 at 15:18, Emil Velikov <emil.l.velikov at gmail.com> wrote:
> On 11 July 2017 at 14:27, Emil Velikov <emil.l.velikov at gmail.com> wrote:
>> According to the EGL_KHR_platform_gbm extension:
>>
>>     For each EGLConfig that belongs to the GBM platform, the
>>     EGL_NATIVE_VISUAL_ID attribute is a GBM color format, such as
>>     GBM_FORMAT_XRGB8888.
>>
>> Which we correctly manage. At the same time the EGL 1.4 spec says
>>
>>     If an EGLConfig supports windows then it may have an associated
>>     native visual. EGL_NATIVE_VISUAL_ID specifies an identifier for this
>>     visual, and EGL_NATIVE_VISUAL_TYPE specifies its type. If an
>>     EGLConfig does not support windows, or if there is no associated
>>     native visual type, then querying EGL_NATIVE_VISUAL_ID will return 0
>>     and querying EGL_NATIVE_VISUAL_TYPE will return EGL_NONE.
>>
>> Based on this, either both of ID and TYPE should be set, or neither.
>>
>> [...]
>
> Does the above make sense? Should we bother?
> Admittedly the stable tag could be dropped, since it's not that
> crucial of a fix.

Did this come up in CTS or similar, or was it just by inspection? I
don't read 0 to mean 'unset'; if an X11 StaticGray visual gets added
(admittedly extremely unlikely), that would have a NATIVE_VISUAL_TYPE
of 0, so there would be precedent for the type being 0.

My take on it is that the visual types are defined by the platform,
and 0 is a perfectly sensible visual type for a platform which does
not actually have any.

Cheers,
Daniel