|
|
<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>wrap_around</structfield>, <structfield>spacing</structfield>,
<structfield>rangelow</structfield> and <structfield>rangehigh</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>The <structfield>rangelow</structfield> and
<structfield>rangehigh</structfield> fields can be set to a non-zero value to
tell the driver to search a specific band. If the &v4l2-tuner;
<structfield>capability</structfield> field has the
<constant>V4L2_TUNER_CAP_HWSEEK_PROG_LIM</constant> flag set, these values
must fall within one of the bands returned by &VIDIOC-ENUM-FREQ-BANDS;. If
the <constant>V4L2_TUNER_CAP_HWSEEK_PROG_LIM</constant> flag is not set,
then these values must exactly match those of one of the bands returned by
&VIDIOC-ENUM-FREQ-BANDS;. If the current frequency of the tuner does not fall
within the selected band it will be clamped to fit in the band before the
seek is started.</para>
<para>If an error is returned, then the original frequency will
be restored.</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>__u32</entry>
<entry><structfield>type</structfield></entry>
<entry>The tuner type. This is the same value as in the
&v4l2-tuner; <structfield>type</structfield> field. See <xref
linkend="v4l2-tuner-type" /></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.
The &v4l2-tuner; <structfield>capability</structfield> field will tell you what the
hardware supports.
</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>rangelow</structfield></entry>
<entry>If non-zero, the lowest tunable frequency of the band to
search in units of 62.5 kHz, or if the &v4l2-tuner;
<structfield>capability</structfield> field has the
<constant>V4L2_TUNER_CAP_LOW</constant> flag set, in units of 62.5 Hz.
If <structfield>rangelow</structfield> is zero a reasonable default value
is used.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>rangehigh</structfield></entry>
<entry>If non-zero, the highest tunable frequency of the band to
search in units of 62.5 kHz, or if the &v4l2-tuner;
<structfield>capability</structfield> field has the
<constant>V4L2_TUNER_CAP_LOW</constant> flag set, in units of 62.5 Hz.
If <structfield>rangehigh</structfield> is zero a reasonable default value
is used.</entry>
</row>
<row>
<entry>__u32</entry>
<entry><structfield>reserved</structfield>[5]</entry>
<entry>Reserved for future extensions. 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, the <structfield>wrap_around</structfield> value is not supported or
one of the values in the <structfield>type</structfield>,
<structfield>rangelow</structfield> or <structfield>rangehigh</structfield>
fields is wrong.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><errorcode>ENODATA</errorcode></term>
<listitem>
<para>The hardware seek found no channels.</para>
</listitem>
</varlistentry>
<varlistentry>
<term><errorcode>EBUSY</errorcode></term>
<listitem>
<para>Another hardware seek is already in progress.</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1>
</refentry>
|
