[media] Spec: document CREATE_BUFS behavior if count == 0
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
diff --git a/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml b/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
index a2474ec..5e73b1c 100644
--- a/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
@@ -97,7 +97,13 @@
<row>
<entry>__u32</entry>
<entry><structfield>count</structfield></entry>
- <entry>The number of buffers requested or granted.</entry>
+ <entry>The number of buffers requested or granted. If count == 0, then
+ <constant>VIDIOC_CREATE_BUFS</constant> will set <structfield>index</structfield>
+ to the current number of created buffers, and it will check the validity of
+ <structfield>memory</structfield> and <structfield>format.type</structfield>.
+ If those are invalid -1 is returned and errno is set to &EINVAL;,
+ otherwise <constant>VIDIOC_CREATE_BUFS</constant> returns 0. It will
+ never set errno to &EBUSY; in this particular case.</entry>
</row>
<row>
<entry>__u32</entry>