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authorSimon Farnsworth <simon.farnsworth@onelan.co.uk>2014-10-31 12:48:42 -0300
committerMauro Carvalho Chehab <mchehab@osg.samsung.com>2014-11-03 14:47:47 -0200
commit9fd1f310a13ab16034cbda4f874eafadc8f80caf (patch)
treee4814a3fa8ed690d1be2a61782559056ff316795 /Documentation
parent847713ea4fc10b3e5f36b5e9f4aadb4155a7f90e (diff)
[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>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/DocBook/media/v4l/io.xml5
1 files changed, 4 insertions, 1 deletions
diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml
index e5e8325aa3d7..1c17f802b471 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.&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>