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

[Mauro Rossi]

2017-03-30 16:17 GMT+02:00 Emil Velikov <emil.l.velikov at gmail.com>:

> 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 ?
>

After applying last version of Tomasz patch,
I could not boot nougat-x86, the same way as per Tapani get_back_bo()
throwing and EGL_BAD_ALLOC
which is a show stopper for surfaceflinger

So I reverted [1] and now I can boot and I also see the black wallpaper
like Tapani.
dumpsys SurfaceFlinger output shows a buffer allocated,
but for some reason both HWC and GLES composition (used in nougat-x86) show
black wallpaper.

----
h/w composer state:
  h/w composer not present and enabled
Allocated buffers:
...
0x7b60f301e380: 29440.00 KiB | 2880 (2944) x 2560 |        5 | 0x00000900 |
com.android.systemui.ImageWallpaper
...
Total allocated (estimate): 54728.50 KB
----


>
> 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,
> other?) separate from the functionality changes ?
>
> -Emil
>

I'd also kindly request to confirm the test environment used to verify
Tomasz patch v2,
which in my understanding has been the following, common between ChomiumOS
and Android-IA:

   - minigbm based gralloc
   - dma FDs for buffers
   - kernel based explicit fences with FDs
   - HWC2 for compositing
   - (?) Render nodes - but I don't know if/when they are used

In android-x86 (nougat-x86) situation is the following:

   - drm_gralloc based gralloc
   - buffer handles
   - Not 100% sure about sync/fences, but I don't recall about using
   explicit fences with FDs
   - GLES for compositing
   - we don't use render nodes

Pardon me if this seems a long checklist or if it's not 100% accurate,
but I would assume that this patch should just work Out-Of-The-Box with
android-x86 (nougat-x86)
even if most of CrOS/Android-IA optimizations are not (yet) used there.

Is this assumption correct?

In this moment the only way to boot nougat-x86 is to revert [1]
but besides this and black wallpaper, which both require investigation,
I've not seen any particular regression.

Thanks for feeedbacks
Mauro

PS: Question for Tapani: if you apply Tomasz patch and revert [1], do you
still see the segfault in Android-IA?

[1]  https://cgit.freedesktop.org/mesa/mesa/commit/?id=
4d4558411db166d2d66f8cec9cb581149dbe1597
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