[Mesa-dev] [RFC] mesa: drop current draw/read buffer when ctx is released

[Emil Velikov]

On 28 October 2016 at 13:22, Rob Clark <robdclark at gmail.com> wrote:
> On Fri, Oct 28, 2016 at 1:24 AM, Tapani Pälli <tapani.palli at intel.com> wrote:
>> On 10/27/2016 01:48 PM, Rob Clark wrote:
>>>
>>> On Thu, Oct 27, 2016 at 2:59 AM, Tapani Pälli <tapani.palli at intel.com>
>>> wrote:
>>>>
>>>> On 10/27/2016 12:16 AM, Rob Clark wrote:
>>>>>
>>>>> So, not quite sure if this is the *correct* solution, but it is at least
>>>>> *a* solution to a problem with android wallpaper vs mesa that I've been
>>>>> debugging.  Basically, what happens is:
>>>>
>>>>
>>>> Could you tell more how to trigger this, is this with some particular
>>>> live
>>>> wallpaper and has this been working before (regression)? For me at least
>>>> these default wallpapers have been working ok.
>>>
>>> Actually, it is the default static wallpaper that is problematic.  And
>>> IIRC, it has never worked, at least not with any of the gallium
>>> drivers (freedreno, virgl, vc4, etc).  Live-wallpaper did work, but
>>> does not appear to exist in AOSP builds anymore.
>>>
>>> If this works with i965 on android, I'd be curious how.  Or if you're
>>> android build had some mesa patches that are not upstream?
>>
>>
>> I can confirm that default wallpaper is working on i965. Our Mesa tree
>> currently looks like this:
>>
>> https://github.com/android-ia/external-mesa
>>
>> It's now quite a bit behind though because we were dealing with some
>> non-graphics issues and are planning to rebase soon.
>
> I suppose it is possible that it is triggered by something different
> that mesa/st does vs dri/i965?  Although I find it odd that
> dri2_make_current() would drop the reference to the EGLSurface when
> unbinding ctx, but _mesa_make_current() would not drop the reference
> to the corresponding gl_framebuffer.
>
Precisely my line of thinking as well. Both egl and glx drop the
reference to the objects on !newCtx.

>From a quick look the only place where we unref.
WinSysDrawBuffer/WinSysReadBuffer is in _mesa_free_context_data which
happens on ctx teardown. Which sounds incomplete -  so I'm a bit
curious why/how that i965 works fine.

> Maybe the classic driver is holding an extra reference to the
> EGLSurface so the _eglPutSurface() call in dri2_make_current() does
> not actually drop the last refcnt?  Which would ensure when the window
> surface is created it ends up with a different address..
>
> but, I wonder if you could try w/ Rob Herring's tree.. this is what we
> are using for the upstream kernel + AOSP builds[1]:
>
>   https://github.com/robherring/mesa/commits/android-m
>
> I guess in theory we should both need the same patches on top of
> mesa..  although also I guess we should also just try to get to the
> point where we can both use upstream mesa tree directly.
>
Indeed. Skimming through the android-ia log - can borrow
ENABLE_FLINK_SUPPORT and let drm/gbm gralloc have a static inline
helpers gralloc_drm_get_gem_handle/gralloc_drm_get_prime_fd.
Thus everyone can polish their gralloc (if interested?) while still
having something that works across the board. With similar direction
on the GRALLOC_MODULE_PERFORM_GET_DRM_FD front ?

Although admittedly i965 could/should use gbm_gralloc ;-)

Emil