159 lines
3.5 KiB
ReStructuredText
159 lines
3.5 KiB
ReStructuredText
.. -*- coding: utf-8; mode: rst -*-
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.. _media_ioc_enum_entities:
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*****************************
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ioctl MEDIA_IOC_ENUM_ENTITIES
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*****************************
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Name
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====
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MEDIA_IOC_ENUM_ENTITIES - Enumerate entities and their properties
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Synopsis
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========
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.. c:function:: int ioctl( int fd, MEDIA_IOC_ENUM_ENTITIES, struct media_entity_desc *argp )
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:name: MEDIA_IOC_ENUM_ENTITIES
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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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To query the attributes of an entity, applications set the id field of a
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struct :c:type:`media_entity_desc` structure and
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call the MEDIA_IOC_ENUM_ENTITIES ioctl with a pointer to this
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structure. The driver fills the rest of the structure or returns an
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EINVAL error code when the id is invalid.
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.. _media-ent-id-flag-next:
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Entities can be enumerated by or'ing the id with the
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``MEDIA_ENT_ID_FLAG_NEXT`` flag. The driver will return information
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about the entity with the smallest id strictly larger than the requested
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one ('next entity'), or the ``EINVAL`` error code if there is none.
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Entity IDs can be non-contiguous. Applications must *not* try to
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enumerate entities by calling MEDIA_IOC_ENUM_ENTITIES with increasing
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id's until they get an error.
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.. c:type:: media_entity_desc
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.. tabularcolumns:: |p{1.5cm}|p{1.7cm}|p{1.6cm}|p{1.5cm}|p{11.2cm}|
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.. flat-table:: struct media_entity_desc
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:header-rows: 0
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:stub-columns: 0
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:widths: 1 1 1 1 8
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* - __u32
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- ``id``
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-
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-
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- Entity ID, set by the application. When the ID is or'ed with
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``MEDIA_ENT_ID_FLAG_NEXT``, the driver clears the flag and returns
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the first entity with a larger ID. Do not expect that the ID will
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always be the same for each instance of the device. In other words,
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do not hardcode entity IDs in an application.
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* - char
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- ``name``\ [32]
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-
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-
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- Entity name as an UTF-8 NULL-terminated string. This name must be unique
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within the media topology.
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* - __u32
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- ``type``
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-
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-
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- Entity type, see :ref:`media-entity-functions` for details.
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* - __u32
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- ``revision``
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-
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-
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- Entity revision. Always zero (obsolete)
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* - __u32
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- ``flags``
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-
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-
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- Entity flags, see :ref:`media-entity-flag` for details.
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* - __u32
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- ``group_id``
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-
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-
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- Entity group ID. Always zero (obsolete)
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* - __u16
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- ``pads``
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-
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-
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- Number of pads
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* - __u16
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- ``links``
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-
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-
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- Total number of outbound links. Inbound links are not counted in
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this field.
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* - __u32
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- ``reserved[4]``
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-
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-
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- Reserved for future extensions. Drivers and applications must set
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the array to zero.
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* - union
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* -
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- struct
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- ``dev``
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-
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- Valid for (sub-)devices that create a single device node.
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* -
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-
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- __u32
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- ``major``
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- Device node major number.
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* -
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-
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- __u32
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- ``minor``
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- Device node minor number.
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* -
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- __u8
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- ``raw``\ [184]
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-
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-
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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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EINVAL
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The struct :c:type:`media_entity_desc` ``id``
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references a non-existing entity.
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