Documentation/DocBook/media/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>If an error is returned, then the original frequency will
  62     be restored.</para>
  63
  64     <para>This ioctl is supported if the <constant>V4L2_CAP_HW_FREQ_SEEK</constant> capability is set.</para>
  65
  66     <table pgwide="1" frame="none" id="v4l2-hw-freq-seek">
  67       <title>struct <structname>v4l2_hw_freq_seek</structname></title>
  68       <tgroup cols="3">
  69         &cs-str;
  70         <tbody valign="top">
  71           <row>
  72             <entry>__u32</entry>
  73             <entry><structfield>tuner</structfield></entry>
  74             <entry>The tuner index number. This is the
  75 same value as in the &v4l2-input; <structfield>tuner</structfield>
  76 field and the &v4l2-tuner; <structfield>index</structfield> field.</entry>
  77           </row>
  78           <row>
  79             <entry>__u32</entry>
  80             <entry><structfield>type</structfield></entry>
  81             <entry>The tuner type. This is the same value as in the
  82 &v4l2-tuner; <structfield>type</structfield> field. See <xref
  83             linkend="v4l2-tuner-type" /></entry>
  84           </row>
  85           <row>
  86             <entry>__u32</entry>
  87             <entry><structfield>seek_upward</structfield></entry>
  88             <entry>If non-zero, seek upward from the current frequency, else seek downward.</entry>
  89           </row>
  90           <row>
  91             <entry>__u32</entry>
  92             <entry><structfield>wrap_around</structfield></entry>
  93             <entry>If non-zero, wrap around when at the end of the frequency range, else stop seeking.
  94             The &v4l2-tuner; <structfield>capability</structfield> field will tell you what the
  95             hardware supports.
  96             </entry>
  97           </row>
  98           <row>
  99             <entry>__u32</entry>
 100             <entry><structfield>spacing</structfield></entry>
 101             <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>
 102           </row>
 103           <row>
 104             <entry>__u32</entry>
 105             <entry><structfield>reserved</structfield>[7]</entry>
 106             <entry>Reserved for future extensions. Applications
 107             must set the array to zero.</entry>
 108           </row>
 109         </tbody>
 110       </tgroup>
 111     </table>
 112   </refsect1>
 113
 114   <refsect1>
 115     &return-value;
 116
 117     <variablelist>
 118       <varlistentry>
 119         <term><errorcode>EINVAL</errorcode></term>
 120         <listitem>
 121           <para>The <structfield>tuner</structfield> index is out of
 122 bounds, the wrap_around value is not supported or the value in the <structfield>type</structfield> field is
 123 wrong.</para>
 124         </listitem>
 125       </varlistentry>
 126       <varlistentry>
 127         <term><errorcode>ENODATA</errorcode></term>
 128         <listitem>
 129           <para>The hardware seek found no channels.</para>
 130         </listitem>
 131       </varlistentry>
 132       <varlistentry>
 133         <term><errorcode>EBUSY</errorcode></term>
 134         <listitem>
 135           <para>Another hardware seek is already in progress.</para>
 136         </listitem>
 137       </varlistentry>
 138     </variablelist>
 139   </refsect1>
 140 </refentry>