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authorLinus Torvalds <torvalds@linux-foundation.org>2011-07-30 11:08:53 +0400
committerLinus Torvalds <torvalds@linux-foundation.org>2011-07-30 11:08:53 +0400
commit664a41b8a91bf78a01a751e15175e0008977685a (patch)
treed9dc15c83400ad2dfb430ff27ae3e7fdc9395856 /Documentation/DocBook/media/v4l/vidioc-streamon.xml
parent983236b5741e557451f3ed4ec5ebf1f62a5b2c15 (diff)
parentee2ce3a0b43d14d792d34cf88e7bc2091096744b (diff)
downloadlinux-664a41b8a91bf78a01a751e15175e0008977685a.tar.xz
Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6
* 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-2.6: (430 commits) [media] ir-mce_kbd-decoder: include module.h for its facilities [media] ov5642: include module.h for its facilities [media] em28xx: Fix DVB-C maxsize for em2884 [media] tda18271c2dd: Fix saw filter configuration for DVB-C @6MHz [media] v4l: mt9v032: Fix Bayer pattern [media] V4L: mt9m111: rewrite set_pixfmt [media] V4L: mt9m111: fix missing return value check mt9m111_reg_clear [media] V4L: initial driver for ov5642 CMOS sensor [media] V4L: sh_mobile_ceu_camera: fix Oops when USERPTR mapping fails [media] V4L: soc-camera: remove soc-camera bus and devices on it [media] V4L: soc-camera: un-export the soc-camera bus [media] V4L: sh_mobile_csi2: switch away from using the soc-camera bus notifier [media] V4L: add media bus configuration subdev operations [media] V4L: soc-camera: group struct field initialisations together [media] V4L: soc-camera: remove now unused soc-camera specific PM hooks [media] V4L: pxa-camera: switch to using standard PM hooks [media] NetUP Dual DVB-T/C CI RF: force card hardware revision by module param [media] Don't OOPS if videobuf_dvb_get_frontend return NULL [media] NetUP Dual DVB-T/C CI RF: load firmware according card revision [media] omap3isp: Support configurable HS/VS polarities ... Fix up conflicts: - arch/arm/mach-omap2/board-rx51-peripherals.c: cleanup regulator supply definitions in mach-omap2 vs OMAP3: RX-51: define vdds_csib regulator supply - drivers/staging/tm6000/tm6000-alsa.c (trivial)
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+<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>The buffer<structfield>type</structfield> is not supported,
+ or no buffers have been allocated (memory mapping) or enqueued
+ (output) yet.</para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><errorcode>EPIPE</errorcode></term>
+ <listitem>
+ <para>The driver implements <link
+ linkend="pad-level-formats">pad-level format configuration</link> and
+ the pipeline configuration is invalid.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ </refsect1>
+</refentry>