[media] DocBook media: Clarify V4L2_FIELD_ANY for drivers

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.farnsworth@onelan.co.uk>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>
This commit is contained in:
Simon Farnsworth 2014-10-31 12:48:42 -03:00 committed by Mauro Carvalho Chehab
parent 847713ea4f
commit 9fd1f310a1

View file

@ -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.&nbsp;g. the
requested image size, and return the actual field order. &v4l2-buffer;
requested image size, and return the actual field order. 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;. &v4l2-buffer;
<structfield>field</structfield> can never be
<constant>V4L2_FIELD_ANY</constant>.</entry>
</row>