1 .. -*- coding: utf-8; mode: rst -*-
3 .. _media_ioc_enum_entities:
5 *****************************
6 ioctl MEDIA_IOC_ENUM_ENTITIES
7 *****************************
12 MEDIA_IOC_ENUM_ENTITIES - Enumerate entities and their properties
18 .. c:function:: int ioctl( int fd, MEDIA_IOC_ENUM_ENTITIES, struct media_entity_desc *argp )
19 :name: MEDIA_IOC_ENUM_ENTITIES
26 File descriptor returned by :ref:`open() <media-func-open>`.
29 Pointer to struct :c:type:`media_entity_desc`.
35 To query the attributes of an entity, applications set the id field of a
36 struct :c:type:`media_entity_desc` structure and
37 call the MEDIA_IOC_ENUM_ENTITIES ioctl with a pointer to this
38 structure. The driver fills the rest of the structure or returns an
39 EINVAL error code when the id is invalid.
41 .. _media-ent-id-flag-next:
43 Entities can be enumerated by or'ing the id with the
44 ``MEDIA_ENT_ID_FLAG_NEXT`` flag. The driver will return information
45 about the entity with the smallest id strictly larger than the requested
46 one ('next entity'), or the ``EINVAL`` error code if there is none.
48 Entity IDs can be non-contiguous. Applications must *not* try to
49 enumerate entities by calling MEDIA_IOC_ENUM_ENTITIES with increasing
50 id's until they get an error.
53 .. c:type:: media_entity_desc
55 .. tabularcolumns:: |p{1.5cm}|p{1.7cm}|p{1.6cm}|p{1.5cm}|p{11.2cm}|
57 .. flat-table:: struct media_entity_desc
66 - Entity ID, set by the application. When the ID is or'ed with
67 ``MEDIA_ENT_ID_FLAG_NEXT``, the driver clears the flag and returns
68 the first entity with a larger ID. Do not expect that the ID will
69 always be the same for each instance of the device. In other words,
70 do not hardcode entity IDs in an application.
76 - Entity name as an UTF-8 NULL-terminated string. This name must be unique
77 within the media topology.
83 - Entity type, see :ref:`media-entity-functions` for details.
89 - Entity revision. Always zero (obsolete)
95 - Entity flags, see :ref:`media-entity-flag` for details.
101 - Entity group ID. Always zero (obsolete)
113 - Total number of outbound links. Inbound links are not counted in
120 - Reserved for future extensions. Drivers and applications must set
129 - Valid for (sub-)devices that create a single device node.
135 - Device node major number.
141 - Device node minor number.
153 On success 0 is returned, on error -1 and the ``errno`` variable is set
154 appropriately. The generic error codes are described at the
155 :ref:`Generic Error Codes <gen-errors>` chapter.
158 The struct :c:type:`media_entity_desc` ``id``
159 references a non-existing entity.