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Diffstat (limited to 'Documentation/DocBook/v4l/vidioc-g-frequency.xml')
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diff --git a/Documentation/DocBook/v4l/vidioc-g-frequency.xml b/Documentation/DocBook/v4l/vidioc-g-frequency.xml new file mode 100644 index 000000000000..062d72069090 --- /dev/null +++ b/Documentation/DocBook/v4l/vidioc-g-frequency.xml @@ -0,0 +1,145 @@ +<refentry id="vidioc-g-frequency"> + <refmeta> + <refentrytitle>ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY</refentrytitle> + &manvol; + </refmeta> + + <refnamediv> + <refname>VIDIOC_G_FREQUENCY</refname> + <refname>VIDIOC_S_FREQUENCY</refname> + <refpurpose>Get or set tuner or modulator radio +frequency</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_frequency +*<parameter>argp</parameter></paramdef> + </funcprototype> + </funcsynopsis> + <funcsynopsis> + <funcprototype> + <funcdef>int <function>ioctl</function></funcdef> + <paramdef>int <parameter>fd</parameter></paramdef> + <paramdef>int <parameter>request</parameter></paramdef> + <paramdef>const struct v4l2_frequency +*<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_G_FREQUENCY, VIDIOC_S_FREQUENCY</para> + </listitem> + </varlistentry> + <varlistentry> + <term><parameter>argp</parameter></term> + <listitem> + <para></para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> + + <refsect1> + <title>Description</title> + + <para>To get the current tuner or modulator radio frequency +applications set the <structfield>tuner</structfield> field of a +&v4l2-frequency; to the respective tuner or modulator number (only +input devices have tuners, only output devices have modulators), zero +out the <structfield>reserved</structfield> array and +call the <constant>VIDIOC_G_FREQUENCY</constant> ioctl with a pointer +to this structure. The driver stores the current frequency in the +<structfield>frequency</structfield> field.</para> + + <para>To change the current tuner or modulator radio frequency +applications initialize the <structfield>tuner</structfield>, +<structfield>type</structfield> and +<structfield>frequency</structfield> fields, and the +<structfield>reserved</structfield> array of a &v4l2-frequency; and +call the <constant>VIDIOC_S_FREQUENCY</constant> ioctl with a pointer +to this structure. When the requested frequency is not possible the +driver assumes the closest possible value. However +<constant>VIDIOC_S_FREQUENCY</constant> is a write-only ioctl, it does +not return the actual new frequency.</para> + + <table pgwide="1" frame="none" id="v4l2-frequency"> + <title>struct <structname>v4l2_frequency</structname></title> + <tgroup cols="3"> + &cs-str; + <tbody valign="top"> + <row> + <entry>__u32</entry> + <entry><structfield>tuner</structfield></entry> + <entry>The tuner or modulator index number. This is the +same value as in the &v4l2-input; <structfield>tuner</structfield> +field and the &v4l2-tuner; <structfield>index</structfield> field, or +the &v4l2-output; <structfield>modulator</structfield> field and the +&v4l2-modulator; <structfield>index</structfield> field.</entry> + </row> + <row> + <entry>&v4l2-tuner-type;</entry> + <entry><structfield>type</structfield></entry> + <entry>The tuner type. This is the same value as in the +&v4l2-tuner; <structfield>type</structfield> field. The field is not +applicable to modulators, &ie; ignored by drivers.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>frequency</structfield></entry> + <entry>Tuning frequency in units of 62.5 kHz, or if the +&v4l2-tuner; or &v4l2-modulator; <structfield>capabilities</structfield> flag +<constant>V4L2_TUNER_CAP_LOW</constant> is set, in units of 62.5 +Hz.</entry> + </row> + <row> + <entry>__u32</entry> + <entry><structfield>reserved</structfield>[8]</entry> + <entry>Reserved for future extensions. Drivers and + applications 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 <structfield>tuner</structfield> index is out of +bounds or the value in the <structfield>type</structfield> field is +wrong.</para> + </listitem> + </varlistentry> + </variablelist> + </refsect1> +</refentry> + +<!-- +Local Variables: +mode: sgml +sgml-parent-document: "v4l2.sgml" +indent-tabs-mode: nil +End: +--> |