[media] DocBook: various updates w.r.t. v4l2_buffer and multiplanar
Clarify the behavior of v4l2_buffer in the multiplanar case,
including fixing a false statement: you can't set m.planes to NULL
when calling DQBUF.
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-querybuf.xml b/Documentation/DocBook/media/v4l/vidioc-querybuf.xml
index 6e414d7..a597155 100644
--- a/Documentation/DocBook/media/v4l/vidioc-querybuf.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-querybuf.xml
@@ -48,8 +48,8 @@
<refsect1>
<title>Description</title>
- <para>This ioctl is part of the <link linkend="mmap">memory
-mapping</link> I/O method. It can be used to query the status of a
+ <para>This ioctl is part of the <link linkend="mmap">streaming
+</link> I/O method. It can be used to query the status of a
buffer at any time after buffers have been allocated with the
&VIDIOC-REQBUFS; ioctl.</para>
@@ -71,6 +71,7 @@
<para>In the <structfield>flags</structfield> field the
<constant>V4L2_BUF_FLAG_MAPPED</constant>,
+<constant>V4L2_BUF_FLAG_PREPARED</constant>,
<constant>V4L2_BUF_FLAG_QUEUED</constant> and
<constant>V4L2_BUF_FLAG_DONE</constant> flags will be valid. The
<structfield>memory</structfield> field will be set to the current
@@ -79,8 +80,10 @@
the <structfield>length</structfield> field its size. For the multi-planar API,
fields <structfield>m.mem_offset</structfield> and
<structfield>length</structfield> in the <structfield>m.planes</structfield>
-array elements will be used instead. The driver may or may not set the remaining
-fields and flags, they are meaningless in this context.</para>
+array elements will be used instead and the <structfield>length</structfield>
+field of &v4l2-buffer; is set to the number of filled-in array elements.
+The driver may or may not set the remaining fields and flags, they are
+meaningless in this context.</para>
<para>The <structname>v4l2_buffer</structname> structure is
specified in <xref linkend="buffer" />.</para>