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-rw-r--r--Documentation/DocBook/media/v4l/vidioc-create-bufs.xml28
1 files changed, 18 insertions, 10 deletions
diff --git a/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml b/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
index a2474ecb574..cd994367243 100644
--- a/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
+++ b/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
@@ -6,7 +6,8 @@
<refnamediv>
<refname>VIDIOC_CREATE_BUFS</refname>
- <refpurpose>Create buffers for Memory Mapped or User Pointer I/O</refpurpose>
+ <refpurpose>Create buffers for Memory Mapped or User Pointer or DMA Buffer
+ I/O</refpurpose>
</refnamediv>
<refsynopsisdiv>
@@ -55,16 +56,16 @@
</note>
<para>This ioctl is used to create buffers for <link linkend="mmap">memory
-mapped</link> or <link linkend="userp">user pointer</link>
-I/O. It can be used as an alternative or in addition to the
-<constant>VIDIOC_REQBUFS</constant> ioctl, when a tighter control over buffers
-is required. This ioctl can be called multiple times to create buffers of
-different sizes.</para>
+mapped</link> or <link linkend="userp">user pointer</link> or <link
+linkend="dmabuf">DMA buffer</link> I/O. It can be used as an alternative or in
+addition to the <constant>VIDIOC_REQBUFS</constant> ioctl, when a tighter
+control over buffers is required. This ioctl can be called multiple times to
+create buffers of different sizes.</para>
<para>To allocate device buffers applications initialize relevant fields of
the <structname>v4l2_create_buffers</structname> structure. They set the
<structfield>type</structfield> field in the
-<structname>v4l2_format</structname> structure, embedded in this
+&v4l2-format; structure, embedded in this
structure, to the respective stream or buffer type.
<structfield>count</structfield> must be set to the number of required buffers.
<structfield>memory</structfield> specifies the required I/O method. The
@@ -97,18 +98,25 @@ information.</para>
<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>
<entry><structfield>memory</structfield></entry>
<entry>Applications set this field to
-<constant>V4L2_MEMORY_MMAP</constant> or
+<constant>V4L2_MEMORY_MMAP</constant>,
+<constant>V4L2_MEMORY_DMABUF</constant> or
<constant>V4L2_MEMORY_USERPTR</constant>. See <xref linkend="v4l2-memory"
/></entry>
</row>
<row>
- <entry>struct&nbsp;v4l2_format</entry>
+ <entry>&v4l2-format;</entry>
<entry><structfield>format</structfield></entry>
<entry>Filled in by the application, preserved by the driver.</entry>
</row>