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Diffstat (limited to 'Documentation/DocBook/v4l/vidioc-subdev-enum-frame-interval.xml')
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diff --git a/Documentation/DocBook/v4l/vidioc-subdev-enum-frame-interval.xml b/Documentation/DocBook/v4l/vidioc-subdev-enum-frame-interval.xml new file mode 100644 index 000000000000..2f8f4f0a0235 --- /dev/null +++ b/Documentation/DocBook/v4l/vidioc-subdev-enum-frame-interval.xml @@ -0,0 +1,152 @@ +<refentry id="vidioc-subdev-enum-frame-interval"> + <refmeta> + <refentrytitle>ioctl VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL</refname> + <refpurpose>Enumerate frame intervals</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_subdev_frame_interval_enum * + <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_SUBDEV_ENUM_FRAME_INTERVAL</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <note> + <title>Experimental</title> + <para>This is an <link linkend="experimental">experimental</link> + interface and may change in the future.</para> + </note> + + <para>This ioctl lets applications enumerate available frame intervals on a + given sub-device pad. Frame intervals only makes sense for sub-devices that + can control the frame period on their own. This includes, for instance, + image sensors and TV tuners.</para> + + <para>For the common use case of image sensors, the frame intervals + available on the sub-device output pad depend on the frame format and size + on the same pad. Applications must thus specify the desired format and size + when enumerating frame intervals.</para> + + <para>To enumerate frame intervals applications initialize the + <structfield>index</structfield>, <structfield>pad</structfield>, + <structfield>code</structfield>, <structfield>width</structfield> and + <structfield>height</structfield> fields of + &v4l2-subdev-frame-interval-enum; and call the + <constant>VIDIOC_SUBDEV_ENUM_FRAME_INTERVAL</constant> ioctl with a pointer + to this structure. Drivers fill the rest of the structure or return + an &EINVAL; if one of the input fields is invalid. All frame intervals are + enumerable by beginning at index zero and incrementing by one until + <errorcode>EINVAL</errorcode> is returned.</para> + + <para>Available frame intervals may depend on the current 'try' formats + at other pads of the sub-device, as well as on the current active links. See + &VIDIOC-SUBDEV-G-FMT; for more information about the try formats.</para> + + <para>Sub-devices that support the frame interval enumeration ioctl should + implemented it on a single pad only. Its behaviour when supported on + multiple pads of the same sub-device is not defined.</para> + + <table pgwide="1" frame="none" id="v4l2-subdev-frame-interval-enum"> + <title>struct <structname>v4l2_subdev_frame_interval_enum</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>index</structfield></entry> + <entry>Number of the format in the enumeration, set by the + application.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>pad</structfield></entry> + <entry>Pad number as reported by the media controller API.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>code</structfield></entry> + <entry>The media bus format code, as defined in + <xref linkend="v4l2-mbus-format" />.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>width</structfield></entry> + <entry>Frame width, in pixels.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>height</structfield></entry> + <entry>Frame height, in pixels.</entry> + </row> + <row> + <entry>&v4l2-fract;</entry> + <entry><structfield>interval</structfield></entry> + <entry>Period, in seconds, between consecutive video frames.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[9]</entry> + <entry>Reserved for future extensions. Applications and drivers must + set the array to zero.</entry> + </row> + </tbody> + </tgroup> + </table> + </refsect1> + + <refsect1> + &return-value; + + <variablelist> + <varlistentry> + <term><errorcode>EINVAL</errorcode></term> + <listitem> + <para>The &v4l2-subdev-frame-interval-enum; + <structfield>pad</structfield> references a non-existing pad, one of + the <structfield>code</structfield>, <structfield>width</structfield> + or <structfield>height</structfield> fields are invalid for the given + pad or the <structfield>index</structfield> field is out of bounds. + </para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> |
