linux-vybrid_public/Documentation/DocBook/v4l/vidioc-s-hw-freq-seek.xml

<refentry id="vidioc-s-hw-freq-seek">
  <refmeta>
    <refentrytitle>ioctl VIDIOC_S_HW_FREQ_SEEK</refentrytitle>
    &manvol;
  </refmeta>

  <refnamediv>
    <refname>VIDIOC_S_HW_FREQ_SEEK</refname>
    <refpurpose>Perform a hardware frequency seek</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_hw_freq_seek
*<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_S_HW_FREQ_SEEK</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><parameter>argp</parameter></term>
	<listitem>
	  <para></para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Description</title>

    <para>Start a hardware frequency seek from the current frequency.
To do this applications initialize the <structfield>tuner</structfield>,
<structfield>type</structfield>, <structfield>seek_upward</structfield>,
<structfield>spacing</structfield> and
<structfield>wrap_around</structfield> fields, and zero out the
<structfield>reserved</structfield> array of a &v4l2-hw-freq-seek; and
call the <constant>VIDIOC_S_HW_FREQ_SEEK</constant> ioctl with a pointer
to this structure.</para>

    <para>This ioctl is supported if the <constant>V4L2_CAP_HW_FREQ_SEEK</constant> capability is set.</para>

    <table pgwide="1" frame="none" id="v4l2-hw-freq-seek">
      <title>struct <structname>v4l2_hw_freq_seek</structname></title>
      <tgroup cols="3">
	&cs-str;
	<tbody valign="top">
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>tuner</structfield></entry>
	    <entry>The tuner index number. This is the
same value as in the &v4l2-input; <structfield>tuner</structfield>
field and the &v4l2-tuner; <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.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>seek_upward</structfield></entry>
	    <entry>If non-zero, seek upward from the current frequency, else seek downward.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>wrap_around</structfield></entry>
	    <entry>If non-zero, wrap around when at the end of the frequency range, else stop seeking.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>spacing</structfield></entry>
	    <entry>If non-zero, defines the hardware seek resolution in Hz. The driver selects the nearest value that is supported by the device. If spacing is zero a reasonable default value is used.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>reserved</structfield>[7]</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>
      <varlistentry>
	<term><errorcode>EAGAIN</errorcode></term>
	<listitem>
	  <para>The ioctl timed-out. Try again.</para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>
</refentry>

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