Based on kernel version 4.7.2. Page generated on 2016-08-22 22:45 EST.
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 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>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> 72 fields of a &v4l2-dbg-chip-info; 73 and call <constant>VIDIOC_DBG_G_CHIP_INFO</constant> with a pointer to 74 this structure. On success the driver stores information about the 75 selected 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' 81 on the TV card. You can enumerate all chips by starting at zero and 82 incrementing <structfield>match.addr</structfield> by one until 83 <constant>VIDIOC_DBG_G_CHIP_INFO</constant> fails with an &EINVAL;. 84 The number zero always selects the bridge chip itself, ⪚ the chip 85 connected to the PCI or USB bus. Non-zero numbers identify specific 86 parts 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 91 allows you to enumerate over all sub-devices.</para> 92 93 <para>On success, the <structfield>name</structfield> field will 94 contain a chip name and the <structfield>flags</structfield> field will 95 contain <constant>V4L2_CHIP_FL_READABLE</constant> if the driver supports 96 reading registers from the device or <constant>V4L2_CHIP_FL_WRITABLE</constant> 97 if the driver supports writing registers to the device.</para> 98 99 <para>We recommended the <application>v4l2-dbg</application> 100 utility over calling this ioctl directly. It is available from the 101 LinuxTV v4l-dvb repository; see <ulink 102 url="https://linuxtv.org/repo/">https://linuxtv.org/repo/</ulink> for 103 access 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 116 possible 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 127 to 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 134 to 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> 159 is 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 202 no device could be matched.</para> 203 </listitem> 204 </varlistentry> 205 </variablelist> 206 </refsect1> 207 </refentry>
