mirror of https://gitee.com/openkylin/linux.git
133 lines
4.5 KiB
XML
133 lines
4.5 KiB
XML
<refentry id="media-ioc-device-info">
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<refmeta>
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<refentrytitle>ioctl MEDIA_IOC_DEVICE_INFO</refentrytitle>
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&manvol;
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</refmeta>
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<refnamediv>
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<refname>MEDIA_IOC_DEVICE_INFO</refname>
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<refpurpose>Query device information</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 media_device_info *<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>File descriptor returned by
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<link linkend='media-func-open'><function>open()</function></link>.</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>MEDIA_IOC_DEVICE_INFO</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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<para>All media devices must support the <constant>MEDIA_IOC_DEVICE_INFO</constant>
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ioctl. To query device information, applications call the ioctl with a
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pointer to a &media-device-info;. The driver fills the structure and returns
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the information to the application.
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The ioctl never fails.</para>
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<table pgwide="1" frame="none" id="media-device-info">
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<title>struct <structname>media_device_info</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>char</entry>
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<entry><structfield>driver</structfield>[16]</entry>
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<entry><para>Name of the driver implementing the media API as a
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NUL-terminated ASCII string. The driver version is stored in the
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<structfield>driver_version</structfield> field.</para>
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<para>Driver specific applications can use this information to
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verify the driver identity. It is also useful to work around
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known bugs, or to identify drivers in error reports.</para></entry>
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</row>
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<row>
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<entry>char</entry>
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<entry><structfield>model</structfield>[32]</entry>
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<entry>Device model name as a NUL-terminated UTF-8 string. The
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device version is stored in the <structfield>device_version</structfield>
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field and is not be appended to the model name.</entry>
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</row>
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<row>
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<entry>char</entry>
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<entry><structfield>serial</structfield>[40]</entry>
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<entry>Serial number as a NUL-terminated ASCII string.</entry>
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</row>
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<row>
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<entry>char</entry>
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<entry><structfield>bus_info</structfield>[32]</entry>
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<entry>Location of the device in the system as a NUL-terminated
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ASCII string. This includes the bus type name (PCI, USB, ...) and a
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bus-specific identifier.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>media_version</structfield></entry>
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<entry>Media API version, formatted with the
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<constant>KERNEL_VERSION()</constant> macro.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>hw_revision</structfield></entry>
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<entry>Hardware device revision in a driver-specific format.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>driver_version</structfield></entry>
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<entry>Media device driver version, formatted with the
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<constant>KERNEL_VERSION()</constant> macro. Together with the
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<structfield>driver</structfield> field this identifies a particular
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driver.</entry>
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</row>
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<row>
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<entry>__u32</entry>
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<entry><structfield>reserved</structfield>[31]</entry>
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<entry>Reserved for future extensions. Drivers and applications must
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set this array to zero.</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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<para>The <structfield>serial</structfield> and <structfield>bus_info</structfield>
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fields can be used to distinguish between multiple instances of otherwise
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identical hardware. The serial number takes precedence when provided and can
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be assumed to be unique. If the serial number is an empty string, the
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<structfield>bus_info</structfield> field can be used instead. The
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<structfield>bus_info</structfield> field is guaranteed to be unique, but
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can vary across reboots or device unplug/replug.</para>
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</refsect1>
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<refsect1>
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&return-value;
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</refsect1>
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</refentry>
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