diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-21 09:03:10 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-21 09:03:10 -0700 |
commit | c720f5655df159a630fa0290a0bd67c93e92b0bf (patch) | |
tree | 940d139d0ec1ff5201efddef6cc663166a8a2df3 /Documentation/DocBook/v4l/vidioc-streamon.xml | |
parent | 33e6c1a0de818d3698cdab27c42915661011319d (diff) | |
parent | 84d6ae431f315e8973aac3c3fe1d550fc9240ef3 (diff) |
Merge branch 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6
* 'for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6: (222 commits)
V4L/DVB (13033): pt1: Don't use a deprecated DMA_BIT_MASK macro
V4L/DVB (13029): radio-si4713: remove #include <linux/version.h>
V4L/DVB (13027): go7007: convert printks to v4l2_info
V4L/DVB (13026): s2250-board: Implement brightness and contrast controls
V4L/DVB (13025): s2250-board: Fix memory leaks
V4L/DVB (13024): go7007: Implement vidioc_g_std and vidioc_querystd
V4L/DVB (13023): go7007: Merge struct gofh and go declarations
V4L/DVB (13022): go7007: Fix mpeg controls
V4L/DVB (13021): go7007: Fix whitespace and line lengths
V4L/DVB (13020): go7007: Updates to Kconfig and Makefile
V4L/DVB (13019): video: initial support for ADV7180
V4L/DVB (13018): kzalloc failure ignored in au8522_probe()
V4L/DVB (13017): gspca: kmalloc failure ignored in sd_start()
V4L/DVB (13016): kmalloc failure ignored in lgdt3304_attach() and s921_attach()
V4L/DVB (13015): kmalloc failure ignored in m920x_firmware_download()
V4L/DVB (13014): Add support for Compro VideoMate E800 (DVB-T part only)
V4L/DVB (13013): FM TX: si4713: Kconfig: Fixed two typos.
V4L/DVB (13012): uvc: introduce missing kfree
V4L/DVB (13011): Change tuner type of BeholdTV cards
V4L/DVB (13009): gspca - stv06xx-hdcs: Reduce exposure range
...
Diffstat (limited to 'Documentation/DocBook/v4l/vidioc-streamon.xml')
-rw-r--r-- | Documentation/DocBook/v4l/vidioc-streamon.xml | 106 |
1 files changed, 106 insertions, 0 deletions
diff --git a/Documentation/DocBook/v4l/vidioc-streamon.xml b/Documentation/DocBook/v4l/vidioc-streamon.xml new file mode 100644 index 00000000000..e42bff1f2c0 --- /dev/null +++ b/Documentation/DocBook/v4l/vidioc-streamon.xml @@ -0,0 +1,106 @@ +<refentry id="vidioc-streamon"> + <refmeta> + <refentrytitle>ioctl VIDIOC_STREAMON, VIDIOC_STREAMOFF</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_STREAMON</refname> + <refname>VIDIOC_STREAMOFF</refname> + <refpurpose>Start or stop streaming 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>const int *<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_STREAMON, VIDIOC_STREAMOFF</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>The <constant>VIDIOC_STREAMON</constant> and +<constant>VIDIOC_STREAMOFF</constant> ioctl start and stop the capture +or output process during streaming (<link linkend="mmap">memory +mapping</link> or <link linkend="userp">user pointer</link>) I/O.</para> + + <para>Specifically the capture hardware is disabled and no input +buffers are filled (if there are any empty buffers in the incoming +queue) until <constant>VIDIOC_STREAMON</constant> has been called. +Accordingly the output hardware is disabled, no video signal is +produced until <constant>VIDIOC_STREAMON</constant> has been called. +The ioctl will succeed only when at least one output buffer is in the +incoming queue.</para> + + <para>The <constant>VIDIOC_STREAMOFF</constant> ioctl, apart of +aborting or finishing any DMA in progress, unlocks any user pointer +buffers locked in physical memory, and it removes all buffers from the +incoming and outgoing queues. That means all images captured but not +dequeued yet will be lost, likewise all images enqueued for output but +not transmitted yet. I/O returns to the same state as after calling +&VIDIOC-REQBUFS; and can be restarted accordingly.</para> + + <para>Both ioctls take a pointer to an integer, the desired buffer or +stream type. This is the same as &v4l2-requestbuffers; +<structfield>type</structfield>.</para> + + <para>Note applications can be preempted for unknown periods right +before or after the <constant>VIDIOC_STREAMON</constant> or +<constant>VIDIOC_STREAMOFF</constant> calls, there is no notion of +starting or stopping "now". Buffer timestamps can be used to +synchronize with other events.</para> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>Streaming I/O is not supported, the buffer +<structfield>type</structfield> is not supported, or no buffers have +been allocated (memory mapping) or enqueued (output) yet.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> |