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5>ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY</TITLE
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41>Video for Linux Two API Specification: Revision 0.24</TH
42></TR
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69><HR
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71WIDTH="100%"></DIV
72><H1
73><A
74NAME="VIDIOC-G-FREQUENCY"
75></A
76>ioctl VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY</H1
77><DIV
78CLASS="REFNAMEDIV"
79><A
80NAME="AEN11098"
81></A
82><H2
83>Name</H2
84>VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY&nbsp;--&nbsp;Get or set tuner or modulator radio
85frequency</DIV
86><DIV
87CLASS="REFSYNOPSISDIV"
88><A
89NAME="AEN11102"
90></A
91><H2
92>Synopsis</H2
93><DIV
94CLASS="FUNCSYNOPSIS"
95><P
96></P
97><A
98NAME="AEN11103"
99></A
100><P
101><CODE
102><CODE
103CLASS="FUNCDEF"
104>int ioctl</CODE
105>(int fd, int request, struct v4l2_frequency
106*argp);</CODE
107></P
108><P
109></P
110></DIV
111><DIV
112CLASS="FUNCSYNOPSIS"
113><P
114></P
115><A
116NAME="AEN11113"
117></A
118><P
119><CODE
120><CODE
121CLASS="FUNCDEF"
122>int ioctl</CODE
123>(int fd, int request, const struct v4l2_frequency
124*argp);</CODE
125></P
126><P
127></P
128></DIV
129></DIV
130><DIV
131CLASS="REFSECT1"
132><A
133NAME="AEN11123"
134></A
135><H2
136>Arguments</H2
137><P
138></P
139><DIV
140CLASS="VARIABLELIST"
141><DL
142><DT
143><CODE
144CLASS="PARAMETER"
145>fd</CODE
146></DT
147><DD
148><P
149>File descriptor returned by <A
150HREF="r14090.htm"
151><CODE
152CLASS="FUNCTION"
153>open()</CODE
154></A
155>.</P
156></DD
157><DT
158><CODE
159CLASS="PARAMETER"
160>request</CODE
161></DT
162><DD
163><P
164>VIDIOC_G_FREQUENCY, VIDIOC_S_FREQUENCY</P
165></DD
166><DT
167><CODE
168CLASS="PARAMETER"
169>argp</CODE
170></DT
171><DD
172><P
173></P
174></DD
175></DL
176></DIV
177></DIV
178><DIV
179CLASS="REFSECT1"
180><A
181NAME="AEN11143"
182></A
183><H2
184>Description</H2
185><P
186>To get the current tuner or modulator radio frequency
187applications set the <CODE
188CLASS="STRUCTFIELD"
189>tuner</CODE
190> field of a
191struct&nbsp;<A
192HREF="r11094.htm#V4L2-FREQUENCY"
193>v4l2_frequency</A
194> to the respective tuner or modulator number (only
195input devices have tuners, only output devices have modulators), zero
196out the <CODE
197CLASS="STRUCTFIELD"
198>reserved</CODE
199> array and
200call the <CODE
201CLASS="CONSTANT"
202>VIDIOC_G_FREQUENCY</CODE
203> ioctl with a pointer
204to this structure. The driver stores the current frequency in the
205<CODE
206CLASS="STRUCTFIELD"
207>frequency</CODE
208> field.</P
209><P
210>To change the current tuner or modulator radio frequency
211applications initialize the <CODE
212CLASS="STRUCTFIELD"
213>tuner</CODE
214>,
215<CODE
216CLASS="STRUCTFIELD"
217>type</CODE
218> and
219<CODE
220CLASS="STRUCTFIELD"
221>frequency</CODE
222> fields, and the
223<CODE
224CLASS="STRUCTFIELD"
225>reserved</CODE
226> array of a struct&nbsp;<A
227HREF="r11094.htm#V4L2-FREQUENCY"
228>v4l2_frequency</A
229> and
230call the <CODE
231CLASS="CONSTANT"
232>VIDIOC_S_FREQUENCY</CODE
233> ioctl with a pointer
234to this structure. When the requested frequency is not possible the
235driver assumes the closest possible value. However
236<CODE
237CLASS="CONSTANT"
238>VIDIOC_S_FREQUENCY</CODE
239> is a write-only ioctl, it does
240not return the actual new frequency.</P
241><DIV
242CLASS="TABLE"
243><A
244NAME="V4L2-FREQUENCY"
245></A
246><P
247><B
248>Table 1. struct <CODE
249CLASS="STRUCTNAME"
250>v4l2_frequency</CODE
251></B
252></P
253><TABLE
254BORDER="0"
255FRAME="void"
256WIDTH="100%"
257CLASS="CALSTABLE"
258><COL
259WIDTH="25%"
260TITLE="C1"><COL
261WIDTH="25%"
262TITLE="C2"><COL
263WIDTH="50%"
264TITLE="C3"><TBODY
265VALIGN="TOP"
266><TR
267><TD
268>__u32</TD
269><TD
270><CODE
271CLASS="STRUCTFIELD"
272>tuner</CODE
273></TD
274><TD
275>The tuner or modulator index number. This is the
276same value as in the struct&nbsp;<A
277HREF="r8936.htm#V4L2-INPUT"
278>v4l2_input</A
279> <CODE
280CLASS="STRUCTFIELD"
281>tuner</CODE
282>
283field and the struct&nbsp;<A
284HREF="r12342.htm#V4L2-TUNER"
285>v4l2_tuner</A
286> <CODE
287CLASS="STRUCTFIELD"
288>index</CODE
289> field, or
290the struct&nbsp;<A
291HREF="r9149.htm#V4L2-OUTPUT"
292>v4l2_output</A
293> <CODE
294CLASS="STRUCTFIELD"
295>modulator</CODE
296> field and the
297struct&nbsp;<A
298HREF="r11430.htm#V4L2-MODULATOR"
299>v4l2_modulator</A
300> <CODE
301CLASS="STRUCTFIELD"
302>index</CODE
303> field.</TD
304></TR
305><TR
306><TD
307>enum&nbsp;<A
308HREF="r12342.htm#V4L2-TUNER-TYPE"
309>v4l2_tuner_type</A
310></TD
311><TD
312><CODE
313CLASS="STRUCTFIELD"
314>type</CODE
315></TD
316><TD
317>The tuner type. This is the same value as in the
318struct&nbsp;<A
319HREF="r12342.htm#V4L2-TUNER"
320>v4l2_tuner</A
321> <CODE
322CLASS="STRUCTFIELD"
323>type</CODE
324> field. The field is not
325applicable to modulators, i.&nbsp;e. ignored by drivers.</TD
326></TR
327><TR
328><TD
329>__u32</TD
330><TD
331><CODE
332CLASS="STRUCTFIELD"
333>frequency</CODE
334></TD
335><TD
336>Tuning frequency in units of 62.5 kHz, or if the
337struct&nbsp;<A
338HREF="r12342.htm#V4L2-TUNER"
339>v4l2_tuner</A
340> or struct&nbsp;<A
341HREF="r11430.htm#V4L2-MODULATOR"
342>v4l2_modulator</A
343> <CODE
344CLASS="STRUCTFIELD"
345>capabilities</CODE
346> flag
347<CODE
348CLASS="CONSTANT"
349>V4L2_TUNER_CAP_LOW</CODE
350> is set, in units of 62.5
351Hz.</TD
352></TR
353><TR
354><TD
355>__u32</TD
356><TD
357><CODE
358CLASS="STRUCTFIELD"
359>reserved</CODE
360>[8];</TD
361><TD
362>Reserved for future extensions. Drivers and
363            applications must set the array to zero.</TD
364></TR
365></TBODY
366></TABLE
367></DIV
368></DIV
369><DIV
370CLASS="REFSECT1"
371><A
372NAME="AEN11203"
373></A
374><H2
375>Return Value</H2
376><P
377>On success <SPAN
378CLASS="RETURNVALUE"
379>0</SPAN
380> is returned, on error <SPAN
381CLASS="RETURNVALUE"
382>-1</SPAN
383> and the <CODE
384CLASS="VARNAME"
385>errno</CODE
386> variable is set appropriately:</P
387><P
388></P
389><DIV
390CLASS="VARIABLELIST"
391><DL
392><DT
393><SPAN
394CLASS="ERRORCODE"
395>EINVAL</SPAN
396></DT
397><DD
398><P
399>The <CODE
400CLASS="STRUCTFIELD"
401>tuner</CODE
402> index is out of
403bounds or the value in the <CODE
404CLASS="STRUCTFIELD"
405>type</CODE
406> field is
407wrong.</P
408></DD
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