On 10/31/2014 03:48 PM, Simon Farnsworth wrote:
> Documentation for enum v4l2_field did not make it clear that V4L2_FIELD_ANY
> is only acceptable as input to the kernel, not as a response from the
> driver.
>
> Make it clear, to stop userspace developers like me assuming it can be
> returned by the driver.
>
> Signed-off-by: Simon Farnsworth <simon.farnswo...@onelan.co.uk>
> ---
> Documentation/DocBook/media/v4l/io.xml | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/Documentation/DocBook/media/v4l/io.xml
> b/Documentation/DocBook/media/v4l/io.xml
> index e5e8325..8918bb2 100644
> --- a/Documentation/DocBook/media/v4l/io.xml
> +++ b/Documentation/DocBook/media/v4l/io.xml
> @@ -1422,7 +1422,10 @@ one of the <constant>V4L2_FIELD_NONE</constant>,
> <constant>V4L2_FIELD_BOTTOM</constant>, or
> <constant>V4L2_FIELD_INTERLACED</constant> formats is acceptable.
> Drivers choose depending on hardware capabilities or e. g. the
> -requested image size, and return the actual field order. &v4l2-buffer;
> +requested image size, and return the actual field order. If multiple
> +field orders are possible the driver must choose one of the possible
> +field orders during &VIDIOC-S-FMT; or &VIDIOC-TRY-FMT; and must not
> +return V4L2_FIELD_ANY. &v4l2-buffer;
I would phrase it slightly differently:
"Drivers must never return <constant>V4L2_FIELD_ANY</constant>. If multiple
field orders are possible the driver must choose one of the possible
field orders during &VIDIOC-S-FMT; or &VIDIOC-TRY-FMT;."
Regards,
Hans
> <structfield>field</structfield> can never be
> <constant>V4L2_FIELD_ANY</constant>.</entry>
> </row>
>
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