Re: [PATCH v2 0/1] Virtio Video V4L2 driver

Dmitry Sepp
2020-03-12T09:04:09Z

Hi Hans,

Thanks for reviewing.

Sure, we understand the driver must pass v4l2-compliance. But the spec is not
finalized yet, so it was a bit out of the scope.

Best regards,
Dmitry.

On Mittwoch, 11. März 2020 14:26:46 CET Hans Verkuil wrote:
> Hi Dmitry,
>
> On 2/18/20 9:27 PM, Dmitry Sepp wrote:
> > Hi all,
> >
> > This is a v4l2 virtio video driver for the virtio-video device
> > specification v3 [1].
> >
> > The first version of the driver was introduced here [2].
> >
> > Changes v1 -> v2:
> > * support the v3 spec (mostly)
> > * add a module parameter to ask for pages from ZONE_DMA
> >
> > What is not implemented:
> > * Plane layout flags should be used to propagate number of planes to
> >
> > user-space
> >
> > * There is no real use of stream creation with bitstream format in the
> >
> > parameter list. The driver just uses the first bitstream format from
> > the list.
> >
> > * Setting bitrate is done in a different way compared to the spec. This
> >
> > is because it has been already agreed on that the way the spec
> > currently describes it requires changes.
> >
> > Potential improvements:
> > * Do not send stream_create from open. Use corresponding state machine
> >
> > condition to do this.
> >
> > * Do not send stream_destroy from close. Do it in reqbufs(0).
> > * Cache format and control settings. Reduce calls to the device.
>
> Some general notes:
>
> Before this can be merged it needs to pass v4l2-compliance.
>
> I also strongly recommend adding support for V4L2_PIX_FMT_FWHT to
> allow testing with the vicodec emulation driver. This will also
> allow testing all sorts of corner cases without requiring special
> hardware.
>
> Regards,
>
> Hans
>
> > Best regards,
> > Dmitry.
> >
> > [1] https://markmail.org/message/dmw3pr4fuajvarth
> > [2] https://markmail.org/message/wnnv6r6myvgb5at6