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

[Tapani Pälli]

On 03/31/2017 08:24 AM, Rob Clark wrote:
> 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

Can you give more details, I still live in la la land and don't know 
about 'temp-pbuffer thing'?

// Tapani