aboutsummaryrefslogtreecommitdiffstats
path: root/Documentation/DocBook/media/v4l
diff options
context:
space:
mode:
authorGuennadi Liakhovetski <g.liakhovetski@gmx.de>2011-09-28 08:10:58 -0300
committerMauro Carvalho Chehab <mchehab@redhat.com>2011-11-03 18:28:27 -0200
commit55093284fb6f9009a339e522773417bdd54ec144 (patch)
treec9c91afddcec2fd5890e003e19558f7aa2018979 /Documentation/DocBook/media/v4l
parent21db3e07e1c6302556ae3215ddf0539f5d763b62 (diff)
[media] V4L: document the new VIDIOC_CREATE_BUFS and VIDIOC_PREPARE_BUF ioctl()s
[mchehab@redhat.com: remove emacs format crap at the end of the new files] Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de> Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
Diffstat (limited to 'Documentation/DocBook/media/v4l')
-rw-r--r--Documentation/DocBook/media/v4l/compat.xml3
-rw-r--r--Documentation/DocBook/media/v4l/io.xml27
-rw-r--r--Documentation/DocBook/media/v4l/v4l2.xml2
-rw-r--r--Documentation/DocBook/media/v4l/vidioc-create-bufs.xml139
-rw-r--r--Documentation/DocBook/media/v4l/vidioc-prepare-buf.xml88
5 files changed, 259 insertions, 0 deletions
diff --git a/Documentation/DocBook/media/v4l/compat.xml b/Documentation/DocBook/media/v4l/compat.xml
index 91410b6e7e0..b68698f96e7 100644
--- a/Documentation/DocBook/media/v4l/compat.xml
+++ b/Documentation/DocBook/media/v4l/compat.xml
@@ -2486,6 +2486,9 @@ ioctls.</para>
<listitem>
<para>Flash API. <xref linkend="flash-controls" /></para>
</listitem>
+ <listitem>
+ <para>&VIDIOC-CREATE-BUFS; and &VIDIOC-PREPARE-BUF; ioctls.</para>
+ </listitem>
</itemizedlist>
</section>
diff --git a/Documentation/DocBook/media/v4l/io.xml b/Documentation/DocBook/media/v4l/io.xml
index c57d1ec6291..3f47df1aa54 100644
--- a/Documentation/DocBook/media/v4l/io.xml
+++ b/Documentation/DocBook/media/v4l/io.xml
@@ -927,6 +927,33 @@ ioctl is called.</entry>
Applications set or clear this flag before calling the
<constant>VIDIOC_QBUF</constant> ioctl.</entry>
</row>
+ <row>
+ <entry><constant>V4L2_BUF_FLAG_PREPARED</constant></entry>
+ <entry>0x0400</entry>
+ <entry>The buffer has been prepared for I/O and can be queued by the
+application. Drivers set or clear this flag when the
+<link linkend="vidioc-querybuf">VIDIOC_QUERYBUF</link>, <link
+ linkend="vidioc-qbuf">VIDIOC_PREPARE_BUF</link>, <link
+ linkend="vidioc-qbuf">VIDIOC_QBUF</link> or <link
+ linkend="vidioc-qbuf">VIDIOC_DQBUF</link> ioctl is called.</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_BUF_FLAG_NO_CACHE_INVALIDATE</constant></entry>
+ <entry>0x0400</entry>
+ <entry>Caches do not have to be invalidated for this buffer.
+Typically applications shall use this flag if the data captured in the buffer
+is not going to be touched by the CPU, instead the buffer will, probably, be
+passed on to a DMA-capable hardware unit for further processing or output.
+</entry>
+ </row>
+ <row>
+ <entry><constant>V4L2_BUF_FLAG_NO_CACHE_CLEAN</constant></entry>
+ <entry>0x0800</entry>
+ <entry>Caches do not have to be cleaned for this buffer.
+Typically applications shall use this flag for output buffers if the data
+in this buffer has not been created by the CPU but by some DMA-capable unit,
+in which case caches have not been used.</entry>
+ </row>
</tbody>
</tgroup>
</table>
diff --git a/Documentation/DocBook/media/v4l/v4l2.xml b/Documentation/DocBook/media/v4l/v4l2.xml
index 40132c27764..2ab365c10fb 100644
--- a/Documentation/DocBook/media/v4l/v4l2.xml
+++ b/Documentation/DocBook/media/v4l/v4l2.xml
@@ -469,6 +469,7 @@ and discussions on the V4L mailing list.</revremark>
&sub-close;
&sub-ioctl;
<!-- All ioctls go here. -->
+ &sub-create-bufs;
&sub-cropcap;
&sub-dbg-g-chip-ident;
&sub-dbg-g-register;
@@ -511,6 +512,7 @@ and discussions on the V4L mailing list.</revremark>
&sub-queryctrl;
&sub-query-dv-preset;
&sub-querystd;
+ &sub-prepare-buf;
&sub-reqbufs;
&sub-s-hw-freq-seek;
&sub-streamon;
diff --git a/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml b/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
new file mode 100644
index 00000000000..73ae8a6cd00
--- /dev/null
+++ b/Documentation/DocBook/media/v4l/vidioc-create-bufs.xml
@@ -0,0 +1,139 @@
+<refentry id="vidioc-create-bufs">
+ <refmeta>
+ <refentrytitle>ioctl VIDIOC_CREATE_BUFS</refentrytitle>
+ &manvol;
+ </refmeta>
+
+ <refnamediv>
+ <refname>VIDIOC_CREATE_BUFS</refname>
+ <refpurpose>Create buffers for Memory Mapped or User Pointer I/O</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>int <function>ioctl</function></funcdef>
+ <paramdef>int <parameter>fd</parameter></paramdef>
+ <paramdef>int <parameter>request</parameter></paramdef>
+ <paramdef>struct v4l2_create_buffers *<parameter>argp</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Arguments</title>
+
+ <variablelist>
+ <varlistentry>
+ <term><parameter>fd</parameter></term>
+ <listitem>
+ <para>&fd;</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>request</parameter></term>
+ <listitem>
+ <para>VIDIOC_CREATE_BUFS</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>argp</parameter></term>
+ <listitem>
+ <para></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Description</title>
+
+ <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>
+
+ <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
+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
+<structfield>format</structfield> field shall typically be filled in using
+either the <constant>VIDIOC_TRY_FMT</constant> or
+<constant>VIDIOC_G_FMT</constant> ioctl(). Additionally, applications can adjust
+<structfield>sizeimage</structfield> fields to fit their specific needs. The
+<structfield>reserved</structfield> array must be zeroed.</para>
+
+ <para>When the ioctl is called with a pointer to this structure the driver
+will attempt to allocate up to the requested number of buffers and store the
+actual number allocated and the starting index in the
+<structfield>count</structfield> and the <structfield>index</structfield> fields
+respectively. On return <structfield>count</structfield> can be smaller than
+the number requested. The driver may also increase buffer sizes if required,
+however, it will not update <structfield>sizeimage</structfield> field values.
+The user has to use <constant>VIDIOC_QUERYBUF</constant> to retrieve that
+information.</para>
+
+ <table pgwide="1" frame="none" id="v4l2-create-buffers">
+ <title>struct <structname>v4l2_create_buffers</structname></title>
+ <tgroup cols="3">
+ &cs-str;
+ <tbody valign="top">
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>index</structfield></entry>
+ <entry>The starting buffer index, returned by the driver.</entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>count</structfield></entry>
+ <entry>The number of buffers requested or granted.</entry>
+ </row>
+ <row>
+ <entry>&v4l2-memory;</entry>
+ <entry><structfield>memory</structfield></entry>
+ <entry>Applications set this field to
+<constant>V4L2_MEMORY_MMAP</constant> or
+<constant>V4L2_MEMORY_USERPTR</constant>.</entry>
+ </row>
+ <row>
+ <entry>&v4l2-format;</entry>
+ <entry><structfield>format</structfield></entry>
+ <entry>Filled in by the application, preserved by the driver.</entry>
+ </row>
+ <row>
+ <entry>__u32</entry>
+ <entry><structfield>reserved</structfield>[8]</entry>
+ <entry>A place holder for future extensions.</entry>
+ </row>
+ </tbody>
+ </tgroup>
+ </table>
+ </refsect1>
+
+ <refsect1>
+ &return-value;
+
+ <variablelist>
+ <varlistentry>
+ <term><errorcode>ENOMEM</errorcode></term>
+ <listitem>
+ <para>No memory to allocate buffers for <link linkend="mmap">memory
+mapped</link> I/O.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorcode>EINVAL</errorcode></term>
+ <listitem>
+ <para>The buffer type (<structfield>type</structfield> field) or the
+requested I/O method (<structfield>memory</structfield>) is not
+supported.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+</refentry>
diff --git a/Documentation/DocBook/media/v4l/vidioc-prepare-buf.xml b/Documentation/DocBook/media/v4l/vidioc-prepare-buf.xml
new file mode 100644
index 00000000000..7bde698760e
--- /dev/null
+++ b/Documentation/DocBook/media/v4l/vidioc-prepare-buf.xml
@@ -0,0 +1,88 @@
+<refentry id="vidioc-prepare-buf">
+ <refmeta>
+ <refentrytitle>ioctl VIDIOC_PREPARE_BUF</refentrytitle>
+ &manvol;
+ </refmeta>
+
+ <refnamediv>
+ <refname>VIDIOC_PREPARE_BUF</refname>
+ <refpurpose>Prepare a buffer for I/O</refpurpose>
+ </refnamediv>
+
+ <refsynopsisdiv>
+ <funcsynopsis>
+ <funcprototype>
+ <funcdef>int <function>ioctl</function></funcdef>
+ <paramdef>int <parameter>fd</parameter></paramdef>
+ <paramdef>int <parameter>request</parameter></paramdef>
+ <paramdef>struct v4l2_buffer *<parameter>argp</parameter></paramdef>
+ </funcprototype>
+ </funcsynopsis>
+ </refsynopsisdiv>
+
+ <refsect1>
+ <title>Arguments</title>
+
+ <variablelist>
+ <varlistentry>
+ <term><parameter>fd</parameter></term>
+ <listitem>
+ <para>&fd;</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>request</parameter></term>
+ <listitem>
+ <para>VIDIOC_PREPARE_BUF</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><parameter>argp</parameter></term>
+ <listitem>
+ <para></para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+
+ <refsect1>
+ <title>Description</title>
+
+ <para>Applications can optionally call the
+<constant>VIDIOC_PREPARE_BUF</constant> ioctl to pass ownership of the buffer
+to the driver before actually enqueuing it, using the
+<constant>VIDIOC_QBUF</constant> ioctl, and to prepare it for future I/O.
+Such preparations may include cache invalidation or cleaning. Performing them
+in advance saves time during the actual I/O. In case such cache operations are
+not required, the application can use one of
+<constant>V4L2_BUF_FLAG_NO_CACHE_INVALIDATE</constant> and
+<constant>V4L2_BUF_FLAG_NO_CACHE_CLEAN</constant> flags to skip the respective
+step.</para>
+
+ <para>The <structname>v4l2_buffer</structname> structure is
+specified in <xref linkend="buffer" />.</para>
+ </refsect1>
+
+ <refsect1>
+ &return-value;
+
+ <variablelist>
+ <varlistentry>
+ <term><errorcode>EBUSY</errorcode></term>
+ <listitem>
+ <para>File I/O is in progress.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorcode>EINVAL</errorcode></term>
+ <listitem>
+ <para>The buffer <structfield>type</structfield> is not
+supported, or the <structfield>index</structfield> is out of bounds,
+or no buffers have been allocated yet, or the
+<structfield>userptr</structfield> or
+<structfield>length</structfield> are invalid.</para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+</refentry>