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>,
  55 <structfield>spacing</structfield> and
  56 <structfield>wrap_around</structfield> fields, and zero out the
  57 <structfield>reserved</structfield> array of a &v4l2-hw-freq-seek; and
  58 call the <constant>VIDIOC_S_HW_FREQ_SEEK</constant> ioctl with a pointer
  59 to this structure.</para>
  60
  61     <para>This ioctl is supported if the <constant>V4L2_CAP_HW_FREQ_SEEK</constant> capability is set.</para>
  62
  63     <table pgwide="1" frame="none" id="v4l2-hw-freq-seek">
  64       <title>struct <structname>v4l2_hw_freq_seek</structname></title>
  65       <tgroup cols="3">
  66         &cs-str;
  67         <tbody valign="top">
  68           <row>
  69             <entry>__u32</entry>
  70             <entry><structfield>tuner</structfield></entry>
  71             <entry>The tuner index number. This is the
  72 same value as in the &v4l2-input; <structfield>tuner</structfield>
  73 field and the &v4l2-tuner; <structfield>index</structfield> field.</entry>
  74           </row>
  75           <row>
  76             <entry>&v4l2-tuner-type;</entry>
  77             <entry><structfield>type</structfield></entry>
  78             <entry>The tuner type. This is the same value as in the
  79 &v4l2-tuner; <structfield>type</structfield> field.</entry>
  80           </row>
  81           <row>
  82             <entry>__u32</entry>
  83             <entry><structfield>seek_upward</structfield></entry>
  84             <entry>If non-zero, seek upward from the current frequency, else seek downward.</entry>
  85           </row>
  86           <row>
  87             <entry>__u32</entry>
  88             <entry><structfield>wrap_around</structfield></entry>
  89             <entry>If non-zero, wrap around when at the end of the frequency range, else stop seeking.</entry>
  90           </row>
  91           <row>
  92             <entry>__u32</entry>
  93             <entry><structfield>spacing</structfield></entry>
  94             <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>
  95           </row>
  96           <row>
  97             <entry>__u32</entry>
  98             <entry><structfield>reserved</structfield>[7]</entry>
  99             <entry>Reserved for future extensions. Drivers and
 100             applications must set the array to zero.</entry>
 101           </row>
 102         </tbody>
 103       </tgroup>
 104     </table>
 105   </refsect1>
 106
 107   <refsect1>
 108     &return-value;
 109
 110     <variablelist>
 111       <varlistentry>
 112         <term><errorcode>EINVAL</errorcode></term>
 113         <listitem>
 114           <para>The <structfield>tuner</structfield> index is out of
 115 bounds or the value in the <structfield>type</structfield> field is
 116 wrong.</para>
 117         </listitem>
 118       </varlistentry>
 119       <varlistentry>
 120         <term><errorcode>EAGAIN</errorcode></term>
 121         <listitem>
 122           <para>The ioctl timed-out. Try again.</para>
 123         </listitem>
 124       </varlistentry>
 125     </variablelist>
 126   </refsect1>
 127 </refentry>
 128
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