1 .. Permission is granted to copy, distribute and/or modify this
2 .. document under the terms of the GNU Free Documentation License,
3 .. Version 1.1 or any later version published by the Free Software
4 .. Foundation, with no Invariant Sections, no Front-Cover Texts
5 .. and no Back-Cover Texts. A copy of the license is included at
6 .. Documentation/media/uapi/fdl-appendix.rst.
8 .. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
10 .. _media_ioc_enum_entities:
12 *****************************
13 ioctl MEDIA_IOC_ENUM_ENTITIES
14 *****************************
19 MEDIA_IOC_ENUM_ENTITIES - Enumerate entities and their properties
25 .. c:function:: int ioctl( int fd, MEDIA_IOC_ENUM_ENTITIES, struct media_entity_desc *argp )
26 :name: MEDIA_IOC_ENUM_ENTITIES
33 File descriptor returned by :ref:`open() <media-func-open>`.
36 Pointer to struct :c:type:`media_entity_desc`.
42 To query the attributes of an entity, applications set the id field of a
43 struct :c:type:`media_entity_desc` structure and
44 call the MEDIA_IOC_ENUM_ENTITIES ioctl with a pointer to this
45 structure. The driver fills the rest of the structure or returns an
46 EINVAL error code when the id is invalid.
48 .. _media-ent-id-flag-next:
50 Entities can be enumerated by or'ing the id with the
51 ``MEDIA_ENT_ID_FLAG_NEXT`` flag. The driver will return information
52 about the entity with the smallest id strictly larger than the requested
53 one ('next entity'), or the ``EINVAL`` error code if there is none.
55 Entity IDs can be non-contiguous. Applications must *not* try to
56 enumerate entities by calling MEDIA_IOC_ENUM_ENTITIES with increasing
57 id's until they get an error.
60 .. c:type:: media_entity_desc
62 .. tabularcolumns:: |p{1.5cm}|p{1.7cm}|p{1.6cm}|p{1.5cm}|p{11.2cm}|
64 .. flat-table:: struct media_entity_desc
72 - Entity ID, set by the application. When the ID is or'ed with
73 ``MEDIA_ENT_ID_FLAG_NEXT``, the driver clears the flag and returns
74 the first entity with a larger ID. Do not expect that the ID will
75 always be the same for each instance of the device. In other words,
76 do not hardcode entity IDs in an application.
81 - Entity name as an UTF-8 NULL-terminated string. This name must be unique
82 within the media topology.
87 - Entity type, see :ref:`media-entity-functions` for details.
92 - Entity revision. Always zero (obsolete)
97 - Entity flags, see :ref:`media-entity-flag` for details.
102 - Entity group ID. Always zero (obsolete)
112 - Total number of outbound links. Inbound links are not counted in
118 - Reserved for future extensions. Drivers and applications must set
127 - Valid for (sub-)devices that create a single device node.
132 - Device node major number.
137 - Device node minor number.
150 On success 0 is returned, on error -1 and the ``errno`` variable is set
151 appropriately. The generic error codes are described at the
152 :ref:`Generic Error Codes <gen-errors>` chapter.
155 The struct :c:type:`media_entity_desc` ``id``
156 references a non-existing entity.