[Mesa-dev] [PATCH 0/3] Support for Android RGBX/RGBA formats

[Marek Olšák]

On Sun, Apr 24, 2016 at 2:16 PM, Marek Olšák <maraeo at gmail.com> wrote:
> On Fri, Apr 22, 2016 at 12:41 PM, Chih-Wei Huang
> <cwhuang at android-x86.org> wrote:
>> 2016-04-21 21:42 GMT+08:00 Emil Velikov <emil.l.velikov at gmail.com>:
>>>
>>> On 19 April 2016 at 20:38, Rob Herring <robh at kernel.org> wrote:
>>>> The RGBX/RGBA pixel formats used in the Android EGL don't get configs
>>>> created due to the missing formats in the DRI state tracker. This series
>>>> adds the necessary formats for configs and DRI images. Support in GBM is
>>>> also added as it will be needed soon for Android.
>>>>
>>>> AFAICT, this has been a long standing bug in Android-x86 which was
>>>> worked around with the patch "GLSurfaceView: Be less picky about
>>>> EGLConfig alpha sizes". With this series, this patch is no longer needed
>>>> and several other bugs like wallpaper not getting displayed are fixed.
>>>>
>>> In the past similar changes has caused unexpected bugs and/or pert regressions.
>>>
>>> Although I doubt we'll notice them with the patches on the ML, thus
>>> I've pushed the lot to get some wider testing.
>>>  Please keep an eye for fires ;-)
>>
>> Could these be back-ported to 11.2?
>
> DEFINITELY NOT.
>
> It's too risky and it has already broken GLX.

OK so the problem is libGL ignores the red/green/blue mask, therefore
it doesn't distinguish between BGRA and RGBA. Also, DRI always assumes
it's BGRA on the X server side. This patch series also ignores the
red/green/blue mask for imported buffers. That's why DRI2 mostly
works. I haven't tested DRI3.

libGL could be fixed not to expose RGBA visuals, but that's
insufficient, because Mesa drivers must be loadable by older libGL
too.

The bottom line is st/dri can't expose RGBA, because it would break
Mesa with old libGL.

Unless you guys come up with a solution, I'll have to revert the st/dri change.

Marek