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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
56linkend="experimental">experimental</link> interface and may change in
57the future.</para>
58 </note>
59
60 <para>For driver debugging purposes this ioctl allows test
61applications to query the driver about the chips present on the TV
62card. Regular applications must not use it. When you found a chip
63specific bug, please contact the linux-media mailing list (&v4l-ml;)
64so 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>
69fields of a &v4l2-dbg-chip-ident;
70and call <constant>VIDIOC_DBG_G_CHIP_IDENT</constant> with a pointer to
71this structure. On success the driver stores information about the
72selected chip in the <structfield>ident</structfield> and
73<structfield>revision</structfield> fields. On failure the structure
74remains 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
79on the TV card. You can enumerate all chips by starting at zero and
80incrementing <structfield>match.addr</structfield> by one until
81<constant>VIDIOC_DBG_G_CHIP_IDENT</constant> fails with an &EINVAL;.
82The number zero always selects the host chip, &eg; the chip connected
83to 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.
88For instance
89<constant>"saa7127"</constant> will match any chip
90supported by the saa7127 driver, regardless of its &i2c; bus address.
91When multiple chips supported by the same driver are present, the
92ioctl 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
103on the TV card. You can enumerate all chips by starting at zero and
104incrementing <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
108contain 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
111specific value, or zero if no particular revision is associated with
112this 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
117the 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
125was introduced in Linux 2.6.21, but the API was changed to the
126one described here in 2.6.29.</para>
127
128 <para>We recommended the <application>v4l2-dbg</application>
129utility over calling this ioctl directly. It is available from the
130LinuxTV v4l-dvb repository; see <ulink
131url="http://linuxtv.org/repo/">http://linuxtv.org/repo/</ulink> for
132access 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
145possible 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
156to 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
163to 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
184the 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_HOST</constant></entry>
204 <entry>0</entry>
205 <entry>Match the nth chip on the card, zero for the
206 host chip. Does not match &i2c; chips.</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 </tbody>
224 </tgroup>
225 </table>
226
227 <!-- This is an anonymous enum in media/v4l2-chip-ident.h. -->
228 <table pgwide="1" frame="none" id="chip-ids">
229 <title>Chip Identifiers</title>
230 <tgroup cols="3">
231 &cs-def;
232 <tbody valign="top">
233 <row>
234 <entry><constant>V4L2_IDENT_NONE</constant></entry>
235 <entry>0</entry>
236 <entry>No chip matched.</entry>
237 </row>
238 <row>
239 <entry><constant>V4L2_IDENT_AMBIGUOUS</constant></entry>
240 <entry>1</entry>
241 <entry>Multiple chips matched.</entry>
242 </row>
243 <row>
244 <entry><constant>V4L2_IDENT_UNKNOWN</constant></entry>
245 <entry>2</entry>
246 <entry>A chip is present at this address, but the driver
247could not identify it.</entry>
248 </row>
249 </tbody>
250 </tgroup>
251 </table>
252 </refsect1>
253
254 <refsect1>
255 &return-value;
256
257 <variablelist>
258 <varlistentry>
259 <term><errorcode>EINVAL</errorcode></term>
260 <listitem>
261 <para>The driver does not support this ioctl, or the
262<structfield>match_type</structfield> is invalid.</para>
263 </listitem>
264 </varlistentry>
265 </variablelist>
266 </refsect1>
267</refentry>
268
269<!--
270Local Variables:
271mode: sgml
272sgml-parent-document: "v4l2.sgml"
273indent-tabs-mode: nil
274End:
275-->
generated by cgit v1.2.2 (git 2.25.0) at 2024-11-10 18:34:30 -0500