mirror of https://gitee.com/openkylin/linux.git
277 lines
9.1 KiB
XML
277 lines
9.1 KiB
XML
<refentry id="vidioc-dbg-g-chip-ident">
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<refmeta>
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<refentrytitle>ioctl VIDIOC_DBG_G_CHIP_IDENT</refentrytitle>
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&manvol;
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</refmeta>
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<refnamediv>
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<refname>VIDIOC_DBG_G_CHIP_IDENT</refname>
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<refpurpose>Identify the chips on a TV card</refpurpose>
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</refnamediv>
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<refsynopsisdiv>
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<funcsynopsis>
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<funcprototype>
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<funcdef>int <function>ioctl</function></funcdef>
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<paramdef>int <parameter>fd</parameter></paramdef>
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<paramdef>int <parameter>request</parameter></paramdef>
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<paramdef>struct v4l2_dbg_chip_ident
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*<parameter>argp</parameter></paramdef>
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</funcprototype>
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</funcsynopsis>
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</refsynopsisdiv>
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<refsect1>
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<title>Arguments</title>
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<variablelist>
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<varlistentry>
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<term><parameter>fd</parameter></term>
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<listitem>
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<para>&fd;</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>request</parameter></term>
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<listitem>
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<para>VIDIOC_DBG_G_CHIP_IDENT</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>argp</parameter></term>
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<listitem>
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<para></para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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<refsect1>
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<title>Description</title>
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<note>
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<title>Experimental</title>
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<para>This is an <link
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linkend="experimental">experimental</link> interface and may change in
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the future.</para>
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</note>
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<para>For driver debugging purposes this ioctl allows test
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applications to query the driver about the chips present on the TV
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card. Regular applications must not use it. When you found a chip
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specific bug, please contact the linux-media mailing list (&v4l-ml;)
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so it can be fixed.</para>
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<para>To query the driver applications must initialize the
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<structfield>match.type</structfield> and
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<structfield>match.addr</structfield> or <structfield>match.name</structfield>
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fields of a &v4l2-dbg-chip-ident;
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and call <constant>VIDIOC_DBG_G_CHIP_IDENT</constant> with a pointer to
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this structure. On success the driver stores information about the
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selected chip in the <structfield>ident</structfield> and
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<structfield>revision</structfield> fields. On failure the structure
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remains unchanged.</para>
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<para>When <structfield>match.type</structfield> is
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<constant>V4L2_CHIP_MATCH_HOST</constant>,
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<structfield>match.addr</structfield> selects the nth non-&i2c; chip
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on the TV card. You can enumerate all chips by starting at zero and
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incrementing <structfield>match.addr</structfield> by one until
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<constant>VIDIOC_DBG_G_CHIP_IDENT</constant> fails with an &EINVAL;.
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The number zero always selects the host chip, ⪚ the chip connected
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to the PCI or USB bus.</para>
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<para>When <structfield>match.type</structfield> is
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<constant>V4L2_CHIP_MATCH_I2C_DRIVER</constant>,
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<structfield>match.name</structfield> contains the I2C driver name.
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For instance
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<constant>"saa7127"</constant> will match any chip
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supported by the saa7127 driver, regardless of its &i2c; bus address.
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When multiple chips supported by the same driver are present, the
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ioctl will return <constant>V4L2_IDENT_AMBIGUOUS</constant> in the
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<structfield>ident</structfield> field.</para>
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<para>When <structfield>match.type</structfield> is
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<constant>V4L2_CHIP_MATCH_I2C_ADDR</constant>,
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<structfield>match.addr</structfield> selects a chip by its 7 bit
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&i2c; bus address.</para>
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<para>When <structfield>match.type</structfield> is
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<constant>V4L2_CHIP_MATCH_AC97</constant>,
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<structfield>match.addr</structfield> selects the nth AC97 chip
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on the TV card. You can enumerate all chips by starting at zero and
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incrementing <structfield>match.addr</structfield> by one until
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<constant>VIDIOC_DBG_G_CHIP_IDENT</constant> fails with an &EINVAL;.</para>
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<para>On success, the <structfield>ident</structfield> field will
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contain a chip ID from the Linux
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<filename>media/v4l2-chip-ident.h</filename> header file, and the
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<structfield>revision</structfield> field will contain a driver
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specific value, or zero if no particular revision is associated with
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this chip.</para>
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<para>When the driver could not identify the selected chip,
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<structfield>ident</structfield> will contain
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<constant>V4L2_IDENT_UNKNOWN</constant>. When no chip matched
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the ioctl will succeed but the
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<structfield>ident</structfield> field will contain
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<constant>V4L2_IDENT_NONE</constant>. If multiple chips matched,
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<structfield>ident</structfield> will contain
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<constant>V4L2_IDENT_AMBIGUOUS</constant>. In all these cases the
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<structfield>revision</structfield> field remains unchanged.</para>
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<para>This ioctl is optional, not all drivers may support it. It
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was introduced in Linux 2.6.21, but the API was changed to the
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one described here in 2.6.29.</para>
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<para>We recommended the <application>v4l2-dbg</application>
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utility over calling this ioctl directly. It is available from the
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LinuxTV v4l-dvb repository; see <ulink
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url="http://linuxtv.org/repo/">http://linuxtv.org/repo/</ulink> for
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access instructions.</para>
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<!-- Note for convenience vidioc-dbg-g-register.sgml
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contains a duplicate of this table. -->
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<table pgwide="1" frame="none" id="ident-v4l2-dbg-match">
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<title>struct <structname>v4l2_dbg_match</structname></title>
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<tgroup cols="4">
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&cs-ustr;
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<tbody valign="top">
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<row>
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<entry>__u32</entry>
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<entry><structfield>type</structfield></entry>
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<entry>See <xref linkend="ident-chip-match-types" /> for a list of
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possible types.</entry>
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</row>
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<row>
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<entry>union</entry>
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<entry>(anonymous)</entry>
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</row>
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<row>
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<entry></entry>
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<entry>__u32</entry>
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<entry><structfield>addr</structfield></entry>
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<entry>Match a chip by this number, interpreted according
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to the <structfield>type</structfield> field.</entry>
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</row>
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<row>
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<entry></entry>
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<entry>char</entry>
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<entry><structfield>name[32]</structfield></entry>
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<entry>Match a chip by this name, interpreted according
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to the <structfield>type</structfield> field.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<table pgwide="1" frame="none" id="v4l2-dbg-chip-ident">
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<title>struct <structname>v4l2_dbg_chip_ident</structname></title>
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<tgroup cols="3">
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&cs-str;
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<tbody valign="top">
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<row>
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<entry>struct v4l2_dbg_match</entry>
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<entry><structfield>match</structfield></entry>
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<entry>How to match the chip, see <xref linkend="ident-v4l2-dbg-match" />.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>ident</structfield></entry>
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<entry>A chip identifier as defined in the Linux
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<filename>media/v4l2-chip-ident.h</filename> header file, or one of
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the values from <xref linkend="chip-ids" />.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>revision</structfield></entry>
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<entry>A chip revision, chip and driver specific.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<!-- Note for convenience vidioc-dbg-g-register.sgml
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contains a duplicate of this table. -->
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<table pgwide="1" frame="none" id="ident-chip-match-types">
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<title>Chip Match Types</title>
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<tgroup cols="3">
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&cs-def;
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<tbody valign="top">
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<row>
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<entry><constant>V4L2_CHIP_MATCH_BRIDGE</constant></entry>
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<entry>0</entry>
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<entry>Match the nth chip on the card, zero for the
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bridge chip. Does not match sub-devices.</entry>
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</row>
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<row>
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<entry><constant>V4L2_CHIP_MATCH_I2C_DRIVER</constant></entry>
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<entry>1</entry>
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<entry>Match an &i2c; chip by its driver name.</entry>
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</row>
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<row>
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<entry><constant>V4L2_CHIP_MATCH_I2C_ADDR</constant></entry>
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<entry>2</entry>
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<entry>Match a chip by its 7 bit &i2c; bus address.</entry>
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</row>
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<row>
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<entry><constant>V4L2_CHIP_MATCH_AC97</constant></entry>
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<entry>3</entry>
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<entry>Match the nth anciliary AC97 chip.</entry>
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</row>
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<row>
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<entry><constant>V4L2_CHIP_MATCH_SUBDEV_NAME</constant></entry>
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<entry>4</entry>
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<entry>Match the sub-device by name. Can't be used with this ioctl.</entry>
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</row>
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<row>
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<entry><constant>V4L2_CHIP_MATCH_SUBDEV_IDX</constant></entry>
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<entry>5</entry>
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<entry>Match the nth sub-device. Can't be used with this ioctl.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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<!-- This is an anonymous enum in media/v4l2-chip-ident.h. -->
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<table pgwide="1" frame="none" id="chip-ids">
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<title>Chip Identifiers</title>
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<tgroup cols="3">
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&cs-def;
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<tbody valign="top">
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<row>
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<entry><constant>V4L2_IDENT_NONE</constant></entry>
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<entry>0</entry>
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<entry>No chip matched.</entry>
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</row>
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<row>
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<entry><constant>V4L2_IDENT_AMBIGUOUS</constant></entry>
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<entry>1</entry>
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<entry>Multiple chips matched.</entry>
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</row>
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<row>
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<entry><constant>V4L2_IDENT_UNKNOWN</constant></entry>
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<entry>2</entry>
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<entry>A chip is present at this address, but the driver
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could not identify it.</entry>
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</row>
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</tbody>
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</tgroup>
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</table>
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</refsect1>
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<refsect1>
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&return-value;
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<variablelist>
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<varlistentry>
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<term><errorcode>EINVAL</errorcode></term>
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<listitem>
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<para>The <structfield>match_type</structfield> is invalid.</para>
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</listitem>
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</varlistentry>
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</variablelist>
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</refsect1>
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</refentry>
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