.. -*- coding: utf-8; mode: rst -*-
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.. _media_ioc_device_info:
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***************************
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ioctl MEDIA_IOC_DEVICE_INFO
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***************************
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Name
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====
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MEDIA_IOC_DEVICE_INFO - Query device information
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Synopsis
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========
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.. c:function:: int ioctl( int fd, MEDIA_IOC_DEVICE_INFO, struct media_device_info *argp )
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:name: MEDIA_IOC_DEVICE_INFO
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Arguments
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=========
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``fd``
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File descriptor returned by :ref:`open() <media-func-open>`.
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``argp``
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Description
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===========
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All media devices must support the ``MEDIA_IOC_DEVICE_INFO`` ioctl. To
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query device information, applications call the ioctl with a pointer to
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a struct :c:type:`media_device_info`. The driver
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fills the structure and returns the information to the application. The
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ioctl never fails.
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.. c:type:: media_device_info
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.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
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.. flat-table:: struct media_device_info
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 1 2
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* - char
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- ``driver``\ [16]
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- Name of the driver implementing the media API as a NUL-terminated
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ASCII string. The driver version is stored in the
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``driver_version`` field.
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Driver specific applications can use this information to verify
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the driver identity. It is also useful to work around known bugs,
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or to identify drivers in error reports.
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* - char
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- ``model``\ [32]
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- Device model name as a NUL-terminated UTF-8 string. The device
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version is stored in the ``device_version`` field and is not be
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appended to the model name.
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* - char
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- ``serial``\ [40]
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- Serial number as a NUL-terminated ASCII string.
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* - char
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- ``bus_info``\ [32]
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- Location of the device in the system as a NUL-terminated ASCII
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string. This includes the bus type name (PCI, USB, ...) and a
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bus-specific identifier.
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* - __u32
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- ``media_version``
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- Media API version, formatted with the ``KERNEL_VERSION()`` macro.
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* - __u32
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- ``hw_revision``
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- Hardware device revision in a driver-specific format.
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* - __u32
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- ``driver_version``
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- Media device driver version, formatted with the
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``KERNEL_VERSION()`` macro. Together with the ``driver`` field
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this identifies a particular driver.
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* - __u32
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- ``reserved``\ [31]
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- Reserved for future extensions. Drivers and applications must set
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this array to zero.
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The ``serial`` and ``bus_info`` fields can be used to distinguish
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between multiple instances of otherwise identical hardware. The serial
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number takes precedence when provided and can be assumed to be unique.
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If the serial number is an empty string, the ``bus_info`` field can be
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used instead. The ``bus_info`` field is guaranteed to be unique, but can
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vary across reboots or device unplug/replug.
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Return Value
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============
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On success 0 is returned, on error -1 and the ``errno`` variable is set
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appropriately. The generic error codes are described at the
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:ref:`Generic Error Codes <gen-errors>` chapter.
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