media-ioc-enum-entities.rst

  1.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
  2.. c:namespace:: MC
  3
  4.. _media_ioc_enum_entities:
  5
  6*****************************
  7ioctl MEDIA_IOC_ENUM_ENTITIES
  8*****************************
  9
 10Name
 11====
 12
 13MEDIA_IOC_ENUM_ENTITIES - Enumerate entities and their properties
 14
 15Synopsis
 16========
 17
 18.. c:macro:: MEDIA_IOC_ENUM_ENTITIES
 19
 20``int ioctl(int fd, MEDIA_IOC_ENUM_ENTITIES, struct media_entity_desc *argp)``
 21
 22Arguments
 23=========
 24
 25``fd``
 26    File descriptor returned by :c:func:`open()`.
 27
 28``argp``
 29    Pointer to struct :c:type:`media_entity_desc`.
 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.. c:type:: media_entity_desc
 52
 53.. tabularcolumns:: |p{1.5cm}|p{1.7cm}|p{1.6cm}|p{1.5cm}|p{10.6cm}|
 54
 55.. flat-table:: struct media_entity_desc
 56    :header-rows:  0
 57    :stub-columns: 0
 58    :widths: 2 2 1 8
 59
 60    *  -  __u32
 61       -  ``id``
 62       -
 63       -  Entity ID, set by the application. When the ID is or'ed with
 64	  ``MEDIA_ENT_ID_FLAG_NEXT``, the driver clears the flag and returns
 65	  the first entity with a larger ID. Do not expect that the ID will
 66	  always be the same for each instance of the device. In other words,
 67	  do not hardcode entity IDs in an application.
 68
 69    *  -  char
 70       -  ``name``\ [32]
 71       -
 72       -  Entity name as an UTF-8 NULL-terminated string. This name must be unique
 73          within the media topology.
 74
 75    *  -  __u32
 76       -  ``type``
 77       -
 78       -  Entity type, see :ref:`media-entity-functions` for details.
 79
 80    *  -  __u32
 81       -  ``revision``
 82       -
 83       -  Entity revision. Always zero (obsolete)
 84
 85    *  -  __u32
 86       -  ``flags``
 87       -
 88       -  Entity flags, see :ref:`media-entity-flag` for details.
 89
 90    *  -  __u32
 91       -  ``group_id``
 92       -
 93       -  Entity group ID. Always zero (obsolete)
 94
 95    *  -  __u16
 96       -  ``pads``
 97       -
 98       -  Number of pads
 99
100    *  -  __u16
101       -  ``links``
102       -
103       -  Total number of outbound links. Inbound links are not counted in
104	  this field.
105
106    *  -  __u32
107       -  ``reserved[4]``
108       -
109       -  Reserved for future extensions. Drivers and applications must set
110          the array to zero.
111
112    *  -  union {
113       -  (anonymous)
114
115    *  -  struct
116       -  ``dev``
117       -
118       -  Valid for (sub-)devices that create a single device node.
119
120    *  -
121       -  __u32
122       -  ``major``
123       -  Device node major number.
124
125    *  -
126       -  __u32
127       -  ``minor``
128       -  Device node minor number.
129
130    *  -  __u8
131       -  ``raw``\ [184]
132       -
133       -
134    *  - }
135       -
136
137Return Value
138============
139
140On success 0 is returned, on error -1 and the ``errno`` variable is set
141appropriately. The generic error codes are described at the
142:ref:`Generic Error Codes <gen-errors>` chapter.
143
144EINVAL
145    The struct :c:type:`media_entity_desc` ``id``
146    references a non-existing entity.