aboutsummaryrefslogtreecommitdiff
path: root/Documentation/DocBook/media/v4l/vidioc-dbg-g-chip-ident.xml
blob: 4ecd966808de77a1c66e999322bf420fc8910021 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
<refentry id="vidioc-dbg-g-chip-ident">
  <refmeta>
    <refentrytitle>ioctl VIDIOC_DBG_G_CHIP_IDENT</refentrytitle>
    &manvol;
  </refmeta>

  <refnamediv>
    <refname>VIDIOC_DBG_G_CHIP_IDENT</refname>
    <refpurpose>Identify the chips on a TV card</refpurpose>
  </refnamediv>

  <refsynopsisdiv>
    <funcsynopsis>
      <funcprototype>
	<funcdef>int <function>ioctl</function></funcdef>
	<paramdef>int <parameter>fd</parameter></paramdef>
	<paramdef>int <parameter>request</parameter></paramdef>
	<paramdef>struct v4l2_dbg_chip_ident
*<parameter>argp</parameter></paramdef>
      </funcprototype>
    </funcsynopsis>
  </refsynopsisdiv>

  <refsect1>
    <title>Arguments</title>

    <variablelist>
      <varlistentry>
	<term><parameter>fd</parameter></term>
	<listitem>
	  <para>&fd;</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><parameter>request</parameter></term>
	<listitem>
	  <para>VIDIOC_DBG_G_CHIP_IDENT</para>
	</listitem>
      </varlistentry>
      <varlistentry>
	<term><parameter>argp</parameter></term>
	<listitem>
	  <para></para>
	</listitem>
      </varlistentry>
    </variablelist>
  </refsect1>

  <refsect1>
    <title>Description</title>

    <note>
      <title>Experimental</title>

      <para>This is an <link
linkend="experimental">experimental</link> interface and may change in
the future.</para>
    </note>

    <para>For driver debugging purposes this ioctl allows test
applications to query the driver about the chips present on the TV
card. Regular applications must not use it. When you found a chip
specific bug, please contact the linux-media mailing list (&v4l-ml;)
so it can be fixed.</para>

    <para>To query the driver applications must initialize the
<structfield>match.type</structfield> and
<structfield>match.addr</structfield> or <structfield>match.name</structfield>
fields of a &v4l2-dbg-chip-ident;
and call <constant>VIDIOC_DBG_G_CHIP_IDENT</constant> with a pointer to
this structure. On success the driver stores information about the
selected chip in the <structfield>ident</structfield> and
<structfield>revision</structfield> fields. On failure the structure
remains unchanged.</para>

    <para>When <structfield>match.type</structfield> is
<constant>V4L2_CHIP_MATCH_HOST</constant>,
<structfield>match.addr</structfield> selects the nth non-&i2c; chip
on the TV card. You can enumerate all chips by starting at zero and
incrementing <structfield>match.addr</structfield> by one until
<constant>VIDIOC_DBG_G_CHIP_IDENT</constant> fails with an &EINVAL;.
The number zero always selects the host chip, &eg; the chip connected
to the PCI or USB bus.</para>

    <para>When <structfield>match.type</structfield> is
<constant>V4L2_CHIP_MATCH_I2C_DRIVER</constant>,
<structfield>match.name</structfield> contains the I2C driver name.
For instance
<constant>"saa7127"</constant> will match any chip
supported by the saa7127 driver, regardless of its &i2c; bus address.
When multiple chips supported by the same driver are present, the
ioctl will return <constant>V4L2_IDENT_AMBIGUOUS</constant> in the
<structfield>ident</structfield> field.</para>

    <para>When <structfield>match.type</structfield> is
<constant>V4L2_CHIP_MATCH_I2C_ADDR</constant>,
<structfield>match.addr</structfield> selects a chip by its 7 bit
&i2c; bus address.</para>

    <para>When <structfield>match.type</structfield> is
<constant>V4L2_CHIP_MATCH_AC97</constant>,
<structfield>match.addr</structfield> selects the nth AC97 chip
on the TV card. You can enumerate all chips by starting at zero and
incrementing <structfield>match.addr</structfield> by one until
<constant>VIDIOC_DBG_G_CHIP_IDENT</constant> fails with an &EINVAL;.</para>

    <para>On success, the <structfield>ident</structfield> field will
contain a chip ID from the Linux
<filename>media/v4l2-chip-ident.h</filename> header file, and the
<structfield>revision</structfield> field will contain a driver
specific value, or zero if no particular revision is associated with
this chip.</para>

    <para>When the driver could not identify the selected chip,
<structfield>ident</structfield> will contain
<constant>V4L2_IDENT_UNKNOWN</constant>. When no chip matched
the ioctl will succeed but the
<structfield>ident</structfield> field will contain
<constant>V4L2_IDENT_NONE</constant>. If multiple chips matched,
<structfield>ident</structfield> will contain
<constant>V4L2_IDENT_AMBIGUOUS</constant>. In all these cases the
<structfield>revision</structfield> field remains unchanged.</para>

    <para>This ioctl is optional, not all drivers may support it. It
was introduced in Linux 2.6.21, but the API was changed to the
one described here in 2.6.29.</para>

    <para>We recommended the <application>v4l2-dbg</application>
utility over calling this ioctl directly. It is available from the
LinuxTV v4l-dvb repository; see <ulink
url="http://linuxtv.org/repo/">http://linuxtv.org/repo/</ulink> for
access instructions.</para>

    <!-- Note for convenience vidioc-dbg-g-register.sgml
	 contains a duplicate of this table. -->
    <table pgwide="1" frame="none" id="ident-v4l2-dbg-match">
      <title>struct <structname>v4l2_dbg_match</structname></title>
      <tgroup cols="4">
	&cs-ustr;
	<tbody valign="top">
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>type</structfield></entry>
	    <entry>See <xref linkend="ident-chip-match-types" /> for a list of
possible types.</entry>
	  </row>
	  <row>
	    <entry>union</entry>
	    <entry>(anonymous)</entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry>__u32</entry>
	    <entry><structfield>addr</structfield></entry>
	    <entry>Match a chip by this number, interpreted according
to the <structfield>type</structfield> field.</entry>
	  </row>
	  <row>
	    <entry></entry>
	    <entry>char</entry>
	    <entry><structfield>name[32]</structfield></entry>
	    <entry>Match a chip by this name, interpreted according
to the <structfield>type</structfield> field.</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>

    <table pgwide="1" frame="none" id="v4l2-dbg-chip-ident">
      <title>struct <structname>v4l2_dbg_chip_ident</structname></title>
      <tgroup cols="3">
	&cs-str;
	<tbody valign="top">
	  <row>
	    <entry>struct v4l2_dbg_match</entry>
	    <entry><structfield>match</structfield></entry>
	    <entry>How to match the chip, see <xref linkend="ident-v4l2-dbg-match" />.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>ident</structfield></entry>
	    <entry>A chip identifier as defined in the Linux
<filename>media/v4l2-chip-ident.h</filename> header file, or one of
the values from <xref linkend="chip-ids" />.</entry>
	  </row>
	  <row>
	    <entry>__u32</entry>
	    <entry><structfield>revision</structfield></entry>
	    <entry>A chip revision, chip and driver specific.</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>

    <!-- Note for convenience vidioc-dbg-g-register.sgml
	 contains a duplicate of this table. -->
    <table pgwide="1" frame="none" id="ident-chip-match-types">
      <title>Chip Match Types</title>
      <tgroup cols="3">
	&cs-def;
	<tbody valign="top">
	  <row>
	    <entry><constant>V4L2_CHIP_MATCH_HOST</constant></entry>
	    <entry>0</entry>
	    <entry>Match the nth chip on the card, zero for the
	    host chip. Does not match &i2c; chips.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_CHIP_MATCH_I2C_DRIVER</constant></entry>
	    <entry>1</entry>
	    <entry>Match an &i2c; chip by its driver name.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_CHIP_MATCH_I2C_ADDR</constant></entry>
	    <entry>2</entry>
	    <entry>Match a chip by its 7 bit &i2c; bus address.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_CHIP_MATCH_AC97</constant></entry>
	    <entry>3</entry>
	    <entry>Match the nth anciliary AC97 chip.</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>

    <!-- This is an anonymous enum in media/v4l2-chip-ident.h. -->
    <table pgwide="1" frame="none" id="chip-ids">
      <title>Chip Identifiers</title>
      <tgroup cols="3">
	&cs-def;
	<tbody valign="top">
	  <row>
	    <entry><constant>V4L2_IDENT_NONE</constant></entry>
	    <entry>0</entry>
	    <entry>No chip matched.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_IDENT_AMBIGUOUS</constant></entry>
	    <entry>1</entry>
	    <entry>Multiple chips matched.</entry>
	  </row>
	  <row>
	    <entry><constant>V4L2_IDENT_UNKNOWN</constant></entry>
	    <entry>2</entry>
	    <entry>A chip is present at this address, but the driver
could not identify it.</entry>
	  </row>
	</tbody>
      </tgroup>
    </table>
  </refsect1>

  <refsect1>
    &return-value;

    <variablelist>
      <varlistentry>
	<term><errorcode>EINVAL</errorcode></term>
	<listitem>
	  <para>The <structfield>match_type</structfield> is invalid.</para>
	</listitem>
      </varlistentry>
     </variablelist>
  </refsect1>
</refentry>