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