Documentation/media/uapi/mediactl/media-ioc-enum-entities.rst

   1 .. -*- coding: utf-8; mode: rst -*-
   2
   3 .. _media_ioc_enum_entities:
   4
   5 *****************************
   6 ioctl MEDIA_IOC_ENUM_ENTITIES
   7 *****************************
   8
   9 Name
  10 ====
  11
  12 MEDIA_IOC_ENUM_ENTITIES - Enumerate entities and their properties
  13
  14
  15 Synopsis
  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
  22 Arguments
  23 =========
  24
  25 ``fd``
  26     File descriptor returned by :ref:`open() <media-func-open>`.
  27
  28 ``argp``
  29
  30
  31 Description
  32 ===========
  33
  34 To query the attributes of an entity, applications set the id field of a
  35 struct :c:type:`media_entity_desc` structure and
  36 call the MEDIA_IOC_ENUM_ENTITIES ioctl with a pointer to this
  37 structure. The driver fills the rest of the structure or returns an
  38 EINVAL error code when the id is invalid.
  39
  40 .. _media-ent-id-flag-next:
  41
  42 Entities can be enumerated by or'ing the id with the
  43 ``MEDIA_ENT_ID_FLAG_NEXT`` flag. The driver will return information
  44 about the entity with the smallest id strictly larger than the requested
  45 one ('next entity'), or the ``EINVAL`` error code if there is none.
  46
  47 Entity IDs can be non-contiguous. Applications must *not* try to
  48 enumerate entities by calling MEDIA_IOC_ENUM_ENTITIES with increasing
  49 id's until they get an error.
  50
  51
  52 .. c:type:: media_entity_desc
  53
  54 .. tabularcolumns:: |p{1.5cm}|p{1.5cm}|p{1.5cm}|p{1.5cm}|p{11.5cm}|
  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
  62     -  .. row 1
  63
  64        -  __u32
  65
  66        -  ``id``
  67
  68        -
  69        -
  70        -  Entity id, set by the application. When the id is or'ed with
  71           ``MEDIA_ENT_ID_FLAG_NEXT``, the driver clears the flag and returns
  72           the first entity with a larger id.
  73
  74     -  .. row 2
  75
  76        -  char
  77
  78        -  ``name``\ [32]
  79
  80        -
  81        -
  82        -  Entity name as an UTF-8 NULL-terminated string.
  83
  84     -  .. row 3
  85
  86        -  __u32
  87
  88        -  ``type``
  89
  90        -
  91        -
  92        -  Entity type, see :ref:`media-entity-type` for details.
  93
  94     -  .. row 4
  95
  96        -  __u32
  97
  98        -  ``revision``
  99
 100        -
 101        -
 102        -  Entity revision. Always zero (obsolete)
 103
 104     -  .. row 5
 105
 106        -  __u32
 107
 108        -  ``flags``
 109
 110        -
 111        -
 112        -  Entity flags, see :ref:`media-entity-flag` for details.
 113
 114     -  .. row 6
 115
 116        -  __u32
 117
 118        -  ``group_id``
 119
 120        -
 121        -
 122        -  Entity group ID. Always zero (obsolete)
 123
 124     -  .. row 7
 125
 126        -  __u16
 127
 128        -  ``pads``
 129
 130        -
 131        -
 132        -  Number of pads
 133
 134     -  .. row 8
 135
 136        -  __u16
 137
 138        -  ``links``
 139
 140        -
 141        -
 142        -  Total number of outbound links. Inbound links are not counted in
 143           this field.
 144
 145     -  .. row 9
 146
 147        -  union
 148
 149     -  .. row 10
 150
 151        -
 152        -  struct
 153
 154        -  ``dev``
 155
 156        -
 157        -  Valid for (sub-)devices that create a single device node.
 158
 159     -  .. row 11
 160
 161        -
 162        -
 163        -  __u32
 164
 165        -  ``major``
 166
 167        -  Device node major number.
 168
 169     -  .. row 12
 170
 171        -
 172        -
 173        -  __u32
 174
 175        -  ``minor``
 176
 177        -  Device node minor number.
 178
 179     -  .. row 13
 180
 181        -
 182        -  __u8
 183
 184        -  ``raw``\ [184]
 185
 186        -
 187        -
 188
 189
 190 Return Value
 191 ============
 192
 193 On success 0 is returned, on error -1 and the ``errno`` variable is set
 194 appropriately. The generic error codes are described at the
 195 :ref:`Generic Error Codes <gen-errors>` chapter.
 196
 197 EINVAL
 198     The struct :c:type:`media_entity_desc` ``id``
 199     references a non-existing entity.