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

   1 <refentry id="vidioc-s-hw-freq-seek">
   2   <refmeta>
   3     <refentrytitle>ioctl VIDIOC_S_HW_FREQ_SEEK</refentrytitle>
   4     &manvol;
   5   </refmeta>
   6
   7   <refnamediv>
   8     <refname>VIDIOC_S_HW_FREQ_SEEK</refname>
   9     <refpurpose>Perform a hardware frequency seek</refpurpose>
  10   </refnamediv>
  11
  12   <refsynopsisdiv>
  13     <funcsynopsis>
  14       <funcprototype>
  15         <funcdef>int <function>ioctl</function></funcdef>
  16         <paramdef>int <parameter>fd</parameter></paramdef>
  17         <paramdef>int <parameter>request</parameter></paramdef>
  18         <paramdef>struct v4l2_hw_freq_seek
  19 *<parameter>argp</parameter></paramdef>
  20       </funcprototype>
  21     </funcsynopsis>
  22   </refsynopsisdiv>
  23
  24   <refsect1>
  25     <title>Arguments</title>
  26
  27     <variablelist>
  28       <varlistentry>
  29         <term><parameter>fd</parameter></term>
  30         <listitem>
  31           <para>&fd;</para>
  32         </listitem>
  33       </varlistentry>
  34       <varlistentry>
  35         <term><parameter>request</parameter></term>
  36         <listitem>
  37           <para>VIDIOC_S_HW_FREQ_SEEK</para>
  38         </listitem>
  39       </varlistentry>
  40       <varlistentry>
  41         <term><parameter>argp</parameter></term>
  42         <listitem>
  43           <para></para>
  44         </listitem>
  45       </varlistentry>
  46     </variablelist>
  47   </refsect1>
  48
  49   <refsect1>
  50     <title>Description</title>
  51
  52     <para>Start a hardware frequency seek from the current frequency.
  53 To do this applications initialize the <structfield>tuner</structfield>,
  54 <structfield>type</structfield>, <structfield>seek_upward</structfield> and
  55 <structfield>wrap_around</structfield> fields, and zero out the
  56 <structfield>reserved</structfield> array of a &v4l2-hw-freq-seek; and
  57 call the <constant>VIDIOC_S_HW_FREQ_SEEK</constant> ioctl with a pointer
  58 to this structure.</para>
  59
  60     <para>This ioctl is supported if the <constant>V4L2_CAP_HW_FREQ_SEEK</constant> capability is set.</para>
  61
  62     <table pgwide="1" frame="none" id="v4l2-hw-freq-seek">
  63       <title>struct <structname>v4l2_hw_freq_seek</structname></title>
  64       <tgroup cols="3">
  65         &cs-str;
  66         <tbody valign="top">
  67           <row>
  68             <entry>__u32</entry>
  69             <entry><structfield>tuner</structfield></entry>
  70             <entry>The tuner index number. This is the
  71 same value as in the &v4l2-input; <structfield>tuner</structfield>
  72 field and the &v4l2-tuner; <structfield>index</structfield> field.</entry>
  73           </row>
  74           <row>
  75             <entry>&v4l2-tuner-type;</entry>
  76             <entry><structfield>type</structfield></entry>
  77             <entry>The tuner type. This is the same value as in the
  78 &v4l2-tuner; <structfield>type</structfield> field.</entry>
  79           </row>
  80           <row>
  81             <entry>__u32</entry>
  82             <entry><structfield>seek_upward</structfield></entry>
  83             <entry>If non-zero, seek upward from the current frequency, else seek downward.</entry>
  84           </row>
  85           <row>
  86             <entry>__u32</entry>
  87             <entry><structfield>wrap_around</structfield></entry>
  88             <entry>If non-zero, wrap around when at the end of the frequency range, else stop seeking.</entry>
  89           </row>
  90           <row>
  91             <entry>__u32</entry>
  92             <entry><structfield>reserved</structfield>[8]</entry>
  93             <entry>Reserved for future extensions. Drivers and
  94             applications must set the array to zero.</entry>
  95           </row>
  96         </tbody>
  97       </tgroup>
  98     </table>
  99   </refsect1>
 100
 101   <refsect1>
 102     &return-value;
 103
 104     <variablelist>
 105       <varlistentry>
 106         <term><errorcode>EINVAL</errorcode></term>
 107         <listitem>
 108           <para>The <structfield>tuner</structfield> index is out of
 109 bounds or the value in the <structfield>type</structfield> field is
 110 wrong.</para>
 111         </listitem>
 112       </varlistentry>
 113       <varlistentry>
 114         <term><errorcode>EAGAIN</errorcode></term>
 115         <listitem>
 116           <para>The ioctl timed-out. Try again.</para>
 117         </listitem>
 118       </varlistentry>
 119     </variablelist>
 120   </refsect1>
 121 </refentry>
 122
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