Re: [RFC PATCH 1/2] [media] videodev2: Add V4L2_BUF_FLAG_LAST

[Hans Verkuil <hverkuil@xs4all.nl>]

On 01/22/2015 12:28 PM, Philipp Zabel wrote:
> From: Peter Seiderer <ps.report@gmx.net>
> 
> This v4l2_buffer flag can be used by drivers to mark a capture buffer
> as the last generated buffer, for example after a V4L2_DEC_CMD_STOP
> command was issued.
> 
> Signed-off-by: Peter Seiderer <ps.report@gmx.net>
> Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
> ---
>  include/uapi/linux/videodev2.h | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/include/uapi/linux/videodev2.h b/include/uapi/linux/videodev2.h
> index fbdc360..c642c10 100644
> --- a/include/uapi/linux/videodev2.h
> +++ b/include/uapi/linux/videodev2.h
> @@ -809,6 +809,8 @@ struct v4l2_buffer {
>  #define V4L2_BUF_FLAG_TSTAMP_SRC_MASK		0x00070000
>  #define V4L2_BUF_FLAG_TSTAMP_SRC_EOF		0x00000000
>  #define V4L2_BUF_FLAG_TSTAMP_SRC_SOE		0x00010000
> +/* mem2mem encoder/decoder */
> +#define V4L2_BUF_FLAG_LAST			0x00100000
>  
>  /**
>   * struct v4l2_exportbuffer - export of video buffer as DMABUF file descriptor
> 

You probably knew this, but this should of course be documented in the V4L2
spec. In particular the spec should be clear about *when* the flag is set.

Also, any drivers that need this should be updated as well. Otherwise applications
cannot rely on it.

Regards,

	Hans