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+<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:
+-->