[Mesa-dev] [RFC PATCH] egl/android: Dequeue buffers inside EGL calls

[Rob Clark]

On Fri, Mar 31, 2017 at 12:22 AM, Tapani Pälli <tapani.palli at intel.com> wrote:
>
>
> On 03/30/2017 05:57 PM, Emil Velikov wrote:
>>
>> On 30 March 2017 at 15:30, Tomasz Figa <tfiga at chromium.org> wrote:
>>>
>>> On Thu, Mar 30, 2017 at 11:17 PM, Emil Velikov <emil.l.velikov at gmail.com>
>>> wrote:
>>>>
>>>>
>>>> On 30 March 2017 at 11:55, Tomasz Figa <tfiga at chromium.org> wrote:
>>>>>
>>>>> Android buffer queues can be abandoned, which results in failing to
>>>>> dequeue next buffer. Currently this would fail somewhere deep within
>>>>> the DRI stack calling loader's getBuffers*(), without any error
>>>>> reporting to the client app. However Android framework code relies on
>>>>> proper signaling of this event, so we move buffer dequeue to
>>>>> createWindowSurface() and swapBuffers() call, which can generate proper
>>>>> EGL errors. To keep the performance benefits of delayed buffer
>>>>> handling,
>>>>> if any, fence wait and DRI image creation is kept delayed until
>>>>> getBuffers*() is called by the DRI driver.
>>>>>
>>>> Thank you Tomasz.
>>>>
>>>> I'm fairly confident that this should resolve the crash [in
>>>> swap_buffers] that Mauro was seeing.
>>>> Mauro can you give it a test ?
>>>
>>>
>>> Ah, I actually noticed a problem with existing code, supposedly fixed
>>> by [1], but I'm afraid it's still wrong.
>>>
>>> Current swap_buffers calls get_back_bo(), but doesn't call
>>> update_buffers(), which is the function that should be called before
>>> to actually dequeue a buffer from Android's buffer queue. Given that,
>>> get_back_bo() would simply fail with !dri2_surf->buffer, because no
>>> buffer was dequeued.
>>>
>> Right - I was wondering why we don't hit that on EGL/GBM or EGL/Wayland.
>> From a quick look - may be because EGL/Android drops the dpy mutex in
>> droid_window_enqueue_buffer().
>>
>>> My patch removes update_buffers() and changes the buffer management so
>>> that there is always a buffer dequeued, starting from surface
>>> creation, unless there was an error somewhere.
>>>
>> Of the top of your head - is there something stopping us from using
>> the same method on $other platforms?
>>
>>> [1]
>>> https://cgit.freedesktop.org/mesa/mesa/commit/src/egl/drivers/dri2/platform_android.c?id=4d4558411db166d2d66f8cec9cb581149dbe1597
>>>
>>>>
>>>>
>>>> Not that huge of an expert on the Android specifics, so just a humble
>>>> request:
>>>> Can we seek the code resuffle (droid_{alloc,free}_local_buffer,
>>
>> Oops silly typo - s/seek/split/.
>>
>>>> other?) separate from the functionality changes ?
>>>
>>>
>>> Sure. Thanks for suggestion.
>>>
>> Please give it a day or two for others to comment.
>
>
> I'm trying to debug why this causes our homescreen (wallpaper) to be black.
> Otherwise I haven't seen any issues with these changes.
>

wallpaper seems to be a special sorta hell..  I wonder if there is
somehow some sort of interaction with what I fixed / worked-around in
a5e733c6b52e93de3000647d075f5ca2f55fcb71 ??

Maybe at least try commenting out the temp-pbuffer thing to get max
texture size, and see if that "fixes" things

BR,
-R