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

Hans Verkuil
2020-03-11T13:26:53Z

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
>
>