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Based on kernel version 3.10. Page generated on 2013-07-08 20:09 EST.

1	<refentry id="vidioc-dbg-g-chip-ident">
2	  <refmeta>
3	    <refentrytitle>ioctl VIDIOC_DBG_G_CHIP_IDENT</refentrytitle>
4	    &manvol;
5	  </refmeta>
6	
7	  <refnamediv>
8	    <refname>VIDIOC_DBG_G_CHIP_IDENT</refname>
9	    <refpurpose>Identify the chips on a TV card</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_dbg_chip_ident
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_DBG_G_CHIP_IDENT</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	    <note>
53	      <title>Experimental</title>
54	
55	      <para>This is an <link
56	linkend="experimental">experimental</link> interface and may change in
57	the future.</para>
58	    </note>
59	
60	    <para>For driver debugging purposes this ioctl allows test
61	applications to query the driver about the chips present on the TV
62	card. Regular applications must not use it. When you found a chip
63	specific bug, please contact the linux-media mailing list (&v4l-ml;)
64	so it can be fixed.</para>
65	
66	    <para>To query the driver applications must initialize the
67	<structfield>match.type</structfield> and
68	<structfield>match.addr</structfield> or <structfield>match.name</structfield>
69	fields of a &v4l2-dbg-chip-ident;
70	and call <constant>VIDIOC_DBG_G_CHIP_IDENT</constant> with a pointer to
71	this structure. On success the driver stores information about the
72	selected chip in the <structfield>ident</structfield> and
73	<structfield>revision</structfield> fields. On failure the structure
74	remains unchanged.</para>
75	
76	    <para>When <structfield>match.type</structfield> is
77	<constant>V4L2_CHIP_MATCH_HOST</constant>,
78	<structfield>match.addr</structfield> selects the nth non-&i2c; chip
79	on the TV card. You can enumerate all chips by starting at zero and
80	incrementing <structfield>match.addr</structfield> by one until
81	<constant>VIDIOC_DBG_G_CHIP_IDENT</constant> fails with an &EINVAL;.
82	The number zero always selects the host chip, &eg; the chip connected
83	to the PCI or USB bus.</para>
84	
85	    <para>When <structfield>match.type</structfield> is
86	<constant>V4L2_CHIP_MATCH_I2C_DRIVER</constant>,
87	<structfield>match.name</structfield> contains the I2C driver name.
88	For instance
89	<constant>"saa7127"</constant> will match any chip
90	supported by the saa7127 driver, regardless of its &i2c; bus address.
91	When multiple chips supported by the same driver are present, the
92	ioctl will return <constant>V4L2_IDENT_AMBIGUOUS</constant> in the
93	<structfield>ident</structfield> field.</para>
94	
95	    <para>When <structfield>match.type</structfield> is
96	<constant>V4L2_CHIP_MATCH_I2C_ADDR</constant>,
97	<structfield>match.addr</structfield> selects a chip by its 7 bit
98	&i2c; bus address.</para>
99	
100	    <para>When <structfield>match.type</structfield> is
101	<constant>V4L2_CHIP_MATCH_AC97</constant>,
102	<structfield>match.addr</structfield> selects the nth AC97 chip
103	on the TV card. You can enumerate all chips by starting at zero and
104	incrementing <structfield>match.addr</structfield> by one until
105	<constant>VIDIOC_DBG_G_CHIP_IDENT</constant> fails with an &EINVAL;.</para>
106	
107	    <para>On success, the <structfield>ident</structfield> field will
108	contain a chip ID from the Linux
109	<filename>media/v4l2-chip-ident.h</filename> header file, and the
110	<structfield>revision</structfield> field will contain a driver
111	specific value, or zero if no particular revision is associated with
112	this chip.</para>
113	
114	    <para>When the driver could not identify the selected chip,
115	<structfield>ident</structfield> will contain
116	<constant>V4L2_IDENT_UNKNOWN</constant>. When no chip matched
117	the ioctl will succeed but the
118	<structfield>ident</structfield> field will contain
119	<constant>V4L2_IDENT_NONE</constant>. If multiple chips matched,
120	<structfield>ident</structfield> will contain
121	<constant>V4L2_IDENT_AMBIGUOUS</constant>. In all these cases the
122	<structfield>revision</structfield> field remains unchanged.</para>
123	
124	    <para>This ioctl is optional, not all drivers may support it. It
125	was introduced in Linux 2.6.21, but the API was changed to the
126	one described here in 2.6.29.</para>
127	
128	    <para>We recommended the <application>v4l2-dbg</application>
129	utility over calling this ioctl directly. It is available from the
130	LinuxTV v4l-dvb repository; see <ulink
131	url="http://linuxtv.org/repo/">http://linuxtv.org/repo/</ulink> for
132	access instructions.</para>
133	
134	    <!-- Note for convenience vidioc-dbg-g-register.sgml
135		 contains a duplicate of this table. -->
136	    <table pgwide="1" frame="none" id="ident-v4l2-dbg-match">
137	      <title>struct <structname>v4l2_dbg_match</structname></title>
138	      <tgroup cols="4">
139		&cs-ustr;
140		<tbody valign="top">
141		  <row>
142		    <entry>__u32</entry>
143		    <entry><structfield>type</structfield></entry>
144		    <entry>See <xref linkend="ident-chip-match-types" /> for a list of
145	possible types.</entry>
146		  </row>
147		  <row>
148		    <entry>union</entry>
149		    <entry>(anonymous)</entry>
150		  </row>
151		  <row>
152		    <entry></entry>
153		    <entry>__u32</entry>
154		    <entry><structfield>addr</structfield></entry>
155		    <entry>Match a chip by this number, interpreted according
156	to the <structfield>type</structfield> field.</entry>
157		  </row>
158		  <row>
159		    <entry></entry>
160		    <entry>char</entry>
161		    <entry><structfield>name[32]</structfield></entry>
162		    <entry>Match a chip by this name, interpreted according
163	to the <structfield>type</structfield> field.</entry>
164		  </row>
165		</tbody>
166	      </tgroup>
167	    </table>
168	
169	    <table pgwide="1" frame="none" id="v4l2-dbg-chip-ident">
170	      <title>struct <structname>v4l2_dbg_chip_ident</structname></title>
171	      <tgroup cols="3">
172		&cs-str;
173		<tbody valign="top">
174		  <row>
175		    <entry>struct v4l2_dbg_match</entry>
176		    <entry><structfield>match</structfield></entry>
177		    <entry>How to match the chip, see <xref linkend="ident-v4l2-dbg-match" />.</entry>
178		  </row>
179		  <row>
180		    <entry>__u32</entry>
181		    <entry><structfield>ident</structfield></entry>
182		    <entry>A chip identifier as defined in the Linux
183	<filename>media/v4l2-chip-ident.h</filename> header file, or one of
184	the values from <xref linkend="chip-ids" />.</entry>
185		  </row>
186		  <row>
187		    <entry>__u32</entry>
188		    <entry><structfield>revision</structfield></entry>
189		    <entry>A chip revision, chip and driver specific.</entry>
190		  </row>
191		</tbody>
192	      </tgroup>
193	    </table>
194	
195	    <!-- Note for convenience vidioc-dbg-g-register.sgml
196		 contains a duplicate of this table. -->
197	    <table pgwide="1" frame="none" id="ident-chip-match-types">
198	      <title>Chip Match Types</title>
199	      <tgroup cols="3">
200		&cs-def;
201		<tbody valign="top">
202		  <row>
203		    <entry><constant>V4L2_CHIP_MATCH_BRIDGE</constant></entry>
204		    <entry>0</entry>
205		    <entry>Match the nth chip on the card, zero for the
206		    bridge chip. Does not match sub-devices.</entry>
207		  </row>
208		  <row>
209		    <entry><constant>V4L2_CHIP_MATCH_I2C_DRIVER</constant></entry>
210		    <entry>1</entry>
211		    <entry>Match an &i2c; chip by its driver name.</entry>
212		  </row>
213		  <row>
214		    <entry><constant>V4L2_CHIP_MATCH_I2C_ADDR</constant></entry>
215		    <entry>2</entry>
216		    <entry>Match a chip by its 7 bit &i2c; bus address.</entry>
217		  </row>
218		  <row>
219		    <entry><constant>V4L2_CHIP_MATCH_AC97</constant></entry>
220		    <entry>3</entry>
221		    <entry>Match the nth anciliary AC97 chip.</entry>
222		  </row>
223		  <row>
224		    <entry><constant>V4L2_CHIP_MATCH_SUBDEV</constant></entry>
225		    <entry>4</entry>
226		    <entry>Match the nth sub-device. Can't be used with this ioctl.</entry>
227		  </row>
228		</tbody>
229	      </tgroup>
230	    </table>
231	
232	    <!-- This is an anonymous enum in media/v4l2-chip-ident.h. -->
233	    <table pgwide="1" frame="none" id="chip-ids">
234	      <title>Chip Identifiers</title>
235	      <tgroup cols="3">
236		&cs-def;
237		<tbody valign="top">
238		  <row>
239		    <entry><constant>V4L2_IDENT_NONE</constant></entry>
240		    <entry>0</entry>
241		    <entry>No chip matched.</entry>
242		  </row>
243		  <row>
244		    <entry><constant>V4L2_IDENT_AMBIGUOUS</constant></entry>
245		    <entry>1</entry>
246		    <entry>Multiple chips matched.</entry>
247		  </row>
248		  <row>
249		    <entry><constant>V4L2_IDENT_UNKNOWN</constant></entry>
250		    <entry>2</entry>
251		    <entry>A chip is present at this address, but the driver
252	could not identify it.</entry>
253		  </row>
254		</tbody>
255	      </tgroup>
256	    </table>
257	  </refsect1>
258	
259	  <refsect1>
260	    &return-value;
261	
262	    <variablelist>
263	      <varlistentry>
264		<term><errorcode>EINVAL</errorcode></term>
265		<listitem>
266		  <para>The <structfield>match_type</structfield> is invalid.</para>
267		</listitem>
268	      </varlistentry>
269	     </variablelist>
270	  </refsect1>
271	</refentry>
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