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