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1.. -*- coding: utf-8; mode: rst -*-
2
3.. _media_ioc_enum_entities:
4
5*****************************
6ioctl MEDIA_IOC_ENUM_ENTITIES
7*****************************
8
9Name
10====
11
12MEDIA_IOC_ENUM_ENTITIES - Enumerate entities and their properties
13
14
15Synopsis
16========
17
18.. c:function:: int ioctl( int fd, MEDIA_IOC_ENUM_ENTITIES, struct media_entity_desc *argp )
19    :name: MEDIA_IOC_ENUM_ENTITIES
20
21
22Arguments
23=========
24
25``fd``
26    File descriptor returned by :ref:`open() <media-func-open>`.
27
28``argp``
29
30
31Description
32===========
33
34To query the attributes of an entity, applications set the id field of a
35struct :c:type:`media_entity_desc` structure and
36call the MEDIA_IOC_ENUM_ENTITIES ioctl with a pointer to this
37structure. The driver fills the rest of the structure or returns an
38EINVAL error code when the id is invalid.
39
40.. _media-ent-id-flag-next:
41
42Entities can be enumerated by or'ing the id with the
43``MEDIA_ENT_ID_FLAG_NEXT`` flag. The driver will return information
44about the entity with the smallest id strictly larger than the requested
45one ('next entity'), or the ``EINVAL`` error code if there is none.
46
47Entity IDs can be non-contiguous. Applications must *not* try to
48enumerate entities by calling MEDIA_IOC_ENUM_ENTITIES with increasing
49id's until they get an error.
50
51
52.. c:type:: media_entity_desc
53
54.. tabularcolumns:: |p{1.5cm}|p{1.7cm}|p{1.6cm}|p{1.5cm}|p{11.2cm}|
55
56.. flat-table:: struct media_entity_desc
57    :header-rows:  0
58    :stub-columns: 0
59    :widths: 1 1 1 1 8
60
61    *  -  __u32
62       -  ``id``
63       -
64       -
65       -  Entity ID, set by the application. When the ID is or'ed with
66	  ``MEDIA_ENT_ID_FLAG_NEXT``, the driver clears the flag and returns
67	  the first entity with a larger ID. Do not expect that the ID will
68	  always be the same for each instance of the device. In other words,
69	  do not hardcode entity IDs in an application.
70
71    *  -  char
72       -  ``name``\ [32]
73       -
74       -
75       -  Entity name as an UTF-8 NULL-terminated string. This name must be unique
76          within the media topology.
77
78    *  -  __u32
79       -  ``type``
80       -
81       -
82       -  Entity type, see :ref:`media-entity-functions` for details.
83
84    *  -  __u32
85       -  ``revision``
86       -
87       -
88       -  Entity revision. Always zero (obsolete)
89
90    *  -  __u32
91       -  ``flags``
92       -
93       -
94       -  Entity flags, see :ref:`media-entity-flag` for details.
95
96    *  -  __u32
97       -  ``group_id``
98       -
99       -
100       -  Entity group ID. Always zero (obsolete)
101
102    *  -  __u16
103       -  ``pads``
104       -
105       -
106       -  Number of pads
107
108    *  -  __u16
109       -  ``links``
110       -
111       -
112       -  Total number of outbound links. Inbound links are not counted in
113	  this field.
114
115    *  -  __u32
116       -  ``reserved[4]``
117       -
118       -
119       -  Reserved for future extensions. Drivers and applications must set
120          the array to zero.
121
122    *  -  union
123
124    *  -
125       -  struct
126       -  ``dev``
127       -
128       -  Valid for (sub-)devices that create a single device node.
129
130    *  -
131       -
132       -  __u32
133       -  ``major``
134       -  Device node major number.
135
136    *  -
137       -
138       -  __u32
139       -  ``minor``
140       -  Device node minor number.
141
142    *  -
143       -  __u8
144       -  ``raw``\ [184]
145       -
146       -
147
148
149Return Value
150============
151
152On success 0 is returned, on error -1 and the ``errno`` variable is set
153appropriately. The generic error codes are described at the
154:ref:`Generic Error Codes <gen-errors>` chapter.
155
156EINVAL
157    The struct :c:type:`media_entity_desc` ``id``
158    references a non-existing entity.
159