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.
53To do this applications initialize the <structfield>tuner</structfield>,
54<structfield>type</structfield>, <structfield>seek_upward</structfield>,
55<structfield>wrap_around</structfield>, <structfield>spacing</structfield>,
56<structfield>rangelow</structfield> and <structfield>rangehigh</structfield>
57fields, and zero out the <structfield>reserved</structfield> array of a
58&v4l2-hw-freq-seek; and call the <constant>VIDIOC_S_HW_FREQ_SEEK</constant>
59ioctl with a pointer to this structure.</para>
60
61    <para>The <structfield>rangelow</structfield> and
62<structfield>rangehigh</structfield> fields can be set to a non-zero value to
63tell the driver to search a specific band. If the &v4l2-tuner;
64<structfield>capability</structfield> field has the
65<constant>V4L2_TUNER_CAP_HWSEEK_PROG_LIM</constant> flag set, these values
66must fall within one of the bands returned by &VIDIOC-ENUM-FREQ-BANDS;. If
67the <constant>V4L2_TUNER_CAP_HWSEEK_PROG_LIM</constant> flag is not set,
68then these values must exactly match those of one of the bands returned by
69&VIDIOC-ENUM-FREQ-BANDS;. If the current frequency of the tuner does not fall
70within the selected band it will be clamped to fit in the band before the
71seek is started.</para>
72
73    <para>If an error is returned, then the original frequency will
74    be restored.</para>
75
76    <para>This ioctl is supported if the <constant>V4L2_CAP_HW_FREQ_SEEK</constant> capability is set.</para>
77
78    <para>If this ioctl is called from a non-blocking filehandle, then &EAGAIN; is
79    returned and no seek takes place.</para>
80
81    <table pgwide="1" frame="none" id="v4l2-hw-freq-seek">
82      <title>struct <structname>v4l2_hw_freq_seek</structname></title>
83      <tgroup cols="3">
84	&cs-str;
85	<tbody valign="top">
86	  <row>
87	    <entry>__u32</entry>
88	    <entry><structfield>tuner</structfield></entry>
89	    <entry>The tuner index number. This is the
90same value as in the &v4l2-input; <structfield>tuner</structfield>
91field and the &v4l2-tuner; <structfield>index</structfield> field.</entry>
92	  </row>
93	  <row>
94	    <entry>__u32</entry>
95	    <entry><structfield>type</structfield></entry>
96	    <entry>The tuner type. This is the same value as in the
97&v4l2-tuner; <structfield>type</structfield> field. See <xref
98	    linkend="v4l2-tuner-type" /></entry>
99	  </row>
100	  <row>
101	    <entry>__u32</entry>
102	    <entry><structfield>seek_upward</structfield></entry>
103	    <entry>If non-zero, seek upward from the current frequency, else seek downward.</entry>
104	  </row>
105	  <row>
106	    <entry>__u32</entry>
107	    <entry><structfield>wrap_around</structfield></entry>
108	    <entry>If non-zero, wrap around when at the end of the frequency range, else stop seeking.
109	    The &v4l2-tuner; <structfield>capability</structfield> field will tell you what the
110	    hardware supports.
111	    </entry>
112	  </row>
113	  <row>
114	    <entry>__u32</entry>
115	    <entry><structfield>spacing</structfield></entry>
116	    <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>
117	  </row>
118	  <row>
119	    <entry>__u32</entry>
120	    <entry><structfield>rangelow</structfield></entry>
121	    <entry>If non-zero, the lowest tunable frequency of the band to
122search in units of 62.5 kHz, or if the &v4l2-tuner;
123<structfield>capability</structfield> field has the
124<constant>V4L2_TUNER_CAP_LOW</constant> flag set, in units of 62.5 Hz or if the &v4l2-tuner;
125<structfield>capability</structfield> field has the
126<constant>V4L2_TUNER_CAP_1HZ</constant> flag set, in units of 1 Hz.
127If <structfield>rangelow</structfield> is zero a reasonable default value
128is used.</entry>
129	  </row>
130	  <row>
131	    <entry>__u32</entry>
132	    <entry><structfield>rangehigh</structfield></entry>
133	    <entry>If non-zero, the highest tunable frequency of the band to
134search in units of 62.5 kHz, or if the &v4l2-tuner;
135<structfield>capability</structfield> field has the
136<constant>V4L2_TUNER_CAP_LOW</constant> flag set, in units of 62.5 Hz or if the &v4l2-tuner;
137<structfield>capability</structfield> field has the
138<constant>V4L2_TUNER_CAP_1HZ</constant> flag set, in units of 1 Hz.
139If <structfield>rangehigh</structfield> is zero a reasonable default value
140is used.</entry>
141	  </row>
142	  <row>
143	    <entry>__u32</entry>
144	    <entry><structfield>reserved</structfield>[5]</entry>
145	    <entry>Reserved for future extensions. Applications
146	    must set the array to zero.</entry>
147	  </row>
148	</tbody>
149      </tgroup>
150    </table>
151  </refsect1>
152
153  <refsect1>
154    &return-value;
155
156    <variablelist>
157      <varlistentry>
158	<term><errorcode>EINVAL</errorcode></term>
159	<listitem>
160	  <para>The <structfield>tuner</structfield> index is out of
161bounds, the <structfield>wrap_around</structfield> value is not supported or
162one of the values in the <structfield>type</structfield>,
163<structfield>rangelow</structfield> or <structfield>rangehigh</structfield>
164fields is wrong.</para>
165	</listitem>
166      </varlistentry>
167      <varlistentry>
168	<term><errorcode>EAGAIN</errorcode></term>
169	<listitem>
170	  <para>Attempted to call <constant>VIDIOC_S_HW_FREQ_SEEK</constant>
171	  with the filehandle in non-blocking mode.</para>
172	</listitem>
173      </varlistentry>
174      <varlistentry>
175	<term><errorcode>ENODATA</errorcode></term>
176	<listitem>
177	  <para>The hardware seek found no channels.</para>
178	</listitem>
179      </varlistentry>
180      <varlistentry>
181	<term><errorcode>EBUSY</errorcode></term>
182	<listitem>
183	  <para>Another hardware seek is already in progress.</para>
184	</listitem>
185      </varlistentry>
186    </variablelist>
187  </refsect1>
188</refentry>
189