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- <refentry id="vidioc-dbg-g-chip-info">
- <refmeta>
- <refentrytitle>ioctl VIDIOC_DBG_G_CHIP_INFO</refentrytitle>
- &manvol;
- </refmeta>
- <refnamediv>
- <refname>VIDIOC_DBG_G_CHIP_INFO</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_info
- *<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_INFO</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>Additionally the Linux kernel must be compiled with the
- <constant>CONFIG_VIDEO_ADV_DEBUG</constant> option to enable this ioctl.</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-info;
- and call <constant>VIDIOC_DBG_G_CHIP_INFO</constant> with a pointer to
- this structure. On success the driver stores information about the
- selected chip in the <structfield>name</structfield> and
- <structfield>flags</structfield> fields.</para>
- <para>When <structfield>match.type</structfield> is
- <constant>V4L2_CHIP_MATCH_BRIDGE</constant>,
- <structfield>match.addr</structfield> selects the nth bridge '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_INFO</constant> fails with an &EINVAL;.
- The number zero always selects the bridge chip itself, ⪚ the chip
- connected to the PCI or USB bus. Non-zero numbers identify specific
- parts of the bridge chip such as an AC97 register block.</para>
- <para>When <structfield>match.type</structfield> is
- <constant>V4L2_CHIP_MATCH_SUBDEV</constant>,
- <structfield>match.addr</structfield> selects the nth sub-device. This
- allows you to enumerate over all sub-devices.</para>
- <para>On success, the <structfield>name</structfield> field will
- contain a chip name and the <structfield>flags</structfield> field will
- contain <constant>V4L2_CHIP_FL_READABLE</constant> if the driver supports
- reading registers from the device or <constant>V4L2_CHIP_FL_WRITABLE</constant>
- if the driver supports writing registers to the device.</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="name-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="name-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. Currently unused.</entry>
- </row>
- </tbody>
- </tgroup>
- </table>
- <table pgwide="1" frame="none" id="v4l2-dbg-chip-info">
- <title>struct <structname>v4l2_dbg_chip_info</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="name-v4l2-dbg-match" />.</entry>
- </row>
- <row>
- <entry>char</entry>
- <entry><structfield>name[32]</structfield></entry>
- <entry>The name of the chip.</entry>
- </row>
- <row>
- <entry>__u32</entry>
- <entry><structfield>flags</structfield></entry>
- <entry>Set by the driver. If <constant>V4L2_CHIP_FL_READABLE</constant>
- is set, then the driver supports reading registers from the device. If
- <constant>V4L2_CHIP_FL_WRITABLE</constant> is set, then it supports writing registers.</entry>
- </row>
- <row>
- <entry>__u32</entry>
- <entry><structfield>reserved[8]</structfield></entry>
- <entry>Reserved fields, both application and driver must set these to 0.</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="name-chip-match-types">
- <title>Chip Match Types</title>
- <tgroup cols="3">
- &cs-def;
- <tbody valign="top">
- <row>
- <entry><constant>V4L2_CHIP_MATCH_BRIDGE</constant></entry>
- <entry>0</entry>
- <entry>Match the nth chip on the card, zero for the
- bridge chip. Does not match sub-devices.</entry>
- </row>
- <row>
- <entry><constant>V4L2_CHIP_MATCH_SUBDEV</constant></entry>
- <entry>4</entry>
- <entry>Match the nth sub-device.</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 or
- no device could be matched.</para>
- </listitem>
- </varlistentry>
- </variablelist>
- </refsect1>
- </refentry>
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