Re: [PATH v6 10/10] v4l: Document timestamp buffer flag behaviour

[Hans Verkuil <hverkuil@xs4all.nl>]

Acked-by: Hans Verkuil <hans.verkuil@cisco.com>

Regards,

	Hans

On 03/01/2014 02:17 PM, Sakari Ailus wrote:
> Timestamp buffer flags are constant at the moment. Document them so that 1)
> they're always valid and 2) not changed by the drivers. This leaves room to
> extend the functionality later on if needed.
> 
> Signed-off-by: Sakari Ailus <sakari.ailus@iki.fi>
> ---
>  Documentation/DocBook/media/v4l/io.xml |   14 ++++++++++++++
>  1 file changed, 14 insertions(+)
> 
> diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml
> index d44401c..1bffb1c 100644
> --- a/Documentation/DocBook/media/v4l/io.xml
> +++ b/Documentation/DocBook/media/v4l/io.xml
> @@ -653,6 +653,20 @@ plane, are stored in struct <structname>v4l2_plane</structname> instead.
>  In that case, struct <structname>v4l2_buffer</structname> contains an array of
>  plane structures.</para>
>  
> +    <para>Dequeued video buffers come with timestamps. The driver
> +    decides at which part of the frame and with which clock the
> +    timestamp is taken. Please see flags in the masks
> +    <constant>V4L2_BUF_FLAG_TIMESTAMP_MASK</constant> and
> +    <constant>V4L2_BUF_FLAG_TSTAMP_SRC_MASK</constant> in <xref
> +    linkend="buffer-flags">. These flags are always valid and constant
> +    across all buffers during the whole video stream. Changes in these
> +    flags may take place as a side effect of &VIDIOC-S-INPUT; or
> +    &VIDIOC-S-OUTPUT; however. The
> +    <constant>V4L2_BUF_FLAG_TIMESTAMP_COPY</constant> timestamp type
> +    which is used by e.g. on mem-to-mem devices is an exception to the
> +    rule: the timestamp source flags are copied from the OUTPUT video
> +    buffer to the CAPTURE video buffer.</para>
> +
>      <table frame="none" pgwide="1" id="v4l2-buffer">
>        <title>struct <structname>v4l2_buffer</structname></title>
>        <tgroup cols="4">
>