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1<refentry id="vidioc-dbg-g-chip-info">
2 <refmeta>
3 <refentrytitle>ioctl VIDIOC_DBG_G_CHIP_INFO</refentrytitle>
4 &manvol;
5 </refmeta>
6
7 <refnamediv>
8 <refname>VIDIOC_DBG_G_CHIP_INFO</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_info
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_INFO</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>Additionally the Linux kernel must be compiled with the
67<constant>CONFIG_VIDEO_ADV_DEBUG</constant> option to enable this ioctl.</para>
68
69 <para>To query the driver applications must initialize the
70<structfield>match.type</structfield> and
71<structfield>match.addr</structfield> or <structfield>match.name</structfield>
72fields of a &v4l2-dbg-chip-info;
73and call <constant>VIDIOC_DBG_G_CHIP_INFO</constant> with a pointer to
74this structure. On success the driver stores information about the
75selected chip in the <structfield>name</structfield> and
76<structfield>flags</structfield> fields. On failure the structure
77remains unchanged.</para>
78
79 <para>When <structfield>match.type</structfield> is
80<constant>V4L2_CHIP_MATCH_BRIDGE</constant>,
81<structfield>match.addr</structfield> selects the nth bridge 'chip'
82on the TV card. You can enumerate all chips by starting at zero and
83incrementing <structfield>match.addr</structfield> by one until
84<constant>VIDIOC_DBG_G_CHIP_INFO</constant> fails with an &EINVAL;.
85The number zero always selects the bridge chip itself, &eg; the chip
86connected to the PCI or USB bus. Non-zero numbers identify specific
87parts of the bridge chip such as an AC97 register block.</para>
88
89 <para>When <structfield>match.type</structfield> is
90<constant>V4L2_CHIP_MATCH_SUBDEV</constant>,
91<structfield>match.addr</structfield> selects the nth sub-device. This
92allows you to enumerate over all sub-devices.</para>
93
94 <para>On success, the <structfield>name</structfield> field will
95contain a chip name and the <structfield>flags</structfield> field will
96contain <constant>V4L2_CHIP_FL_READABLE</constant> if the driver supports
97reading registers from the device or <constant>V4L2_CHIP_FL_WRITABLE</constant>
98if the driver supports writing registers to the device.</para>
99
100 <para>We recommended the <application>v4l2-dbg</application>
101utility over calling this ioctl directly. It is available from the
102LinuxTV v4l-dvb repository; see <ulink
103url="http://linuxtv.org/repo/">http://linuxtv.org/repo/</ulink> for
104access instructions.</para>
105
106 <!-- Note for convenience vidioc-dbg-g-register.sgml
107 contains a duplicate of this table. -->
108 <table pgwide="1" frame="none" id="name-v4l2-dbg-match">
109 <title>struct <structname>v4l2_dbg_match</structname></title>
110 <tgroup cols="4">
111 &cs-ustr;
112 <tbody valign="top">
113 <row>
114 <entry>__u32</entry>
115 <entry><structfield>type</structfield></entry>
116 <entry>See <xref linkend="name-chip-match-types" /> for a list of
117possible types.</entry>
118 </row>
119 <row>
120 <entry>union</entry>
121 <entry>(anonymous)</entry>
122 </row>
123 <row>
124 <entry></entry>
125 <entry>__u32</entry>
126 <entry><structfield>addr</structfield></entry>
127 <entry>Match a chip by this number, interpreted according
128to the <structfield>type</structfield> field.</entry>
129 </row>
130 <row>
131 <entry></entry>
132 <entry>char</entry>
133 <entry><structfield>name[32]</structfield></entry>
134 <entry>Match a chip by this name, interpreted according
135to the <structfield>type</structfield> field.</entry>
136 </row>
137 </tbody>
138 </tgroup>
139 </table>
140
141 <table pgwide="1" frame="none" id="v4l2-dbg-chip-info">
142 <title>struct <structname>v4l2_dbg_chip_info</structname></title>
143 <tgroup cols="3">
144 &cs-str;
145 <tbody valign="top">
146 <row>
147 <entry>struct v4l2_dbg_match</entry>
148 <entry><structfield>match</structfield></entry>
149 <entry>How to match the chip, see <xref linkend="name-v4l2-dbg-match" />.</entry>
150 </row>
151 <row>
152 <entry>char</entry>
153 <entry><structfield>name[32]</structfield></entry>
154 <entry>The name of the chip.</entry>
155 </row>
156 <row>
157 <entry>__u32</entry>
158 <entry><structfield>flags</structfield></entry>
159 <entry>Set by the driver. If <constant>V4L2_CHIP_FL_READABLE</constant>
160is set, then the driver supports reading registers from the device. If
161<constant>V4L2_CHIP_FL_WRITABLE</constant> is set, then it supports writing registers.</entry>
162 </row>
163 <row>
164 <entry>__u32</entry>
165 <entry><structfield>reserved[8]</structfield></entry>
166 <entry>Reserved fields, both application and driver must set these to 0.</entry>
167 </row>
168 </tbody>
169 </tgroup>
170 </table>
171
172 <!-- Note for convenience vidioc-dbg-g-register.sgml
173 contains a duplicate of this table. -->
174 <table pgwide="1" frame="none" id="name-chip-match-types">
175 <title>Chip Match Types</title>
176 <tgroup cols="3">
177 &cs-def;
178 <tbody valign="top">
179 <row>
180 <entry><constant>V4L2_CHIP_MATCH_BRIDGE</constant></entry>
181 <entry>0</entry>
182 <entry>Match the nth chip on the card, zero for the
183 bridge chip. Does not match sub-devices.</entry>
184 </row>
185 <row>
186 <entry><constant>V4L2_CHIP_MATCH_I2C_DRIVER</constant></entry>
187 <entry>1</entry>
188 <entry>Match an &i2c; chip by its driver name. Can't be used with this ioctl.</entry>
189 </row>
190 <row>
191 <entry><constant>V4L2_CHIP_MATCH_I2C_ADDR</constant></entry>
192 <entry>2</entry>
193 <entry>Match a chip by its 7 bit &i2c; bus address. Can't be used with this ioctl.</entry>
194 </row>
195 <row>
196 <entry><constant>V4L2_CHIP_MATCH_AC97</constant></entry>
197 <entry>3</entry>
198 <entry>Match the nth anciliary AC97 chip. Can't be used with this ioctl.</entry>
199 </row>
200 <row>
201 <entry><constant>V4L2_CHIP_MATCH_SUBDEV</constant></entry>
202 <entry>4</entry>
203 <entry>Match the nth sub-device.</entry>
204 </row>
205 </tbody>
206 </tgroup>
207 </table>
208 </refsect1>
209
210 <refsect1>
211 &return-value;
212
213 <variablelist>
214 <varlistentry>
215 <term><errorcode>EINVAL</errorcode></term>
216 <listitem>
217 <para>The <structfield>match_type</structfield> is invalid or
218no device could be matched.</para>
219 </listitem>
220 </varlistentry>
221 </variablelist>
222 </refsect1>
223</refentry>
generated by cgit v1.2.2 (git 2.25.0) at 2025-09-13 12:54:53 -0400