[Mesa-dev] Nouveau driver problem when using EGL_LINUX_DMA_BUF_EXT

[Pekka Paalanen]

On Mon, 9 Apr 2018 09:56:43 -0400
Ilia Mirkin <imirkin at alum.mit.edu> wrote:

> On Mon, Apr 9, 2018 at 6:57 AM, Volker Vogelhuber
> <v.vogelhuber at digitalendoscopy.de> wrote:
> > I would have guessed, that the use case would be quite common, as having a
> > Live video source rendered via OpenGL shouldn't be a very special topic and
> > having a zero copy approach should be better than having to copy the data  
> 
> Having a live video source is a pretty special topic. (Esp having one
> that you ever use.)

Hi,

FWIW, in Wayland architecture this would be the preferred path to play
back video. A hardware decoder or a camera provides frames via V4L2
API, which the player app sends to a Wayland compositor as dmabuf fds,
which then imports them via EGL to GL for GPU compositing or directly to
KMS for hardware overlay plane.

Weston the compositor does the EGL import, and should "soon" do the KMS
import as well automatically when possible. It also has a test app
weston-simple-dmabuf-v4l which uses a V4L device to provide dmabuf and
send them to the compositor for importing. It has instructions on how
to set up vivid for testing.

Volker, did you try querying V4L2 for the right pitch, ensure you got
bytes vs. pixels correct, and feed that into
EGL_DMA_BUF_PLANE0_PITCH_EXT?

If Nouveau cannot handle that correctly, it would hopefully refuse the
import.


Thanks,
pq
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