146 lines
3.8 KiB
ReStructuredText
146 lines
3.8 KiB
ReStructuredText
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
|
|
.. c:namespace:: MC
|
|
|
|
.. _media_ioc_enum_links:
|
|
|
|
**************************
|
|
ioctl MEDIA_IOC_ENUM_LINKS
|
|
**************************
|
|
|
|
Name
|
|
====
|
|
|
|
MEDIA_IOC_ENUM_LINKS - Enumerate all pads and links for a given entity
|
|
|
|
Synopsis
|
|
========
|
|
|
|
.. c:macro:: MEDIA_IOC_ENUM_LINKS
|
|
|
|
``int ioctl(int fd, MEDIA_IOC_ENUM_LINKS, struct media_links_enum *argp)``
|
|
|
|
Arguments
|
|
=========
|
|
|
|
``fd``
|
|
File descriptor returned by :c:func:`open()`.
|
|
|
|
``argp``
|
|
Pointer to struct :c:type:`media_links_enum`.
|
|
|
|
Description
|
|
===========
|
|
|
|
To enumerate pads and/or links for a given entity, applications set the
|
|
entity field of a struct :c:type:`media_links_enum`
|
|
structure and initialize the struct
|
|
:c:type:`media_pad_desc` and struct
|
|
:c:type:`media_link_desc` structure arrays pointed by
|
|
the ``pads`` and ``links`` fields. They then call the
|
|
MEDIA_IOC_ENUM_LINKS ioctl with a pointer to this structure.
|
|
|
|
If the ``pads`` field is not NULL, the driver fills the ``pads`` array
|
|
with information about the entity's pads. The array must have enough
|
|
room to store all the entity's pads. The number of pads can be retrieved
|
|
with :ref:`MEDIA_IOC_ENUM_ENTITIES`.
|
|
|
|
If the ``links`` field is not NULL, the driver fills the ``links`` array
|
|
with information about the entity's outbound links. The array must have
|
|
enough room to store all the entity's outbound links. The number of
|
|
outbound links can be retrieved with :ref:`MEDIA_IOC_ENUM_ENTITIES`.
|
|
|
|
Only forward links that originate at one of the entity's source pads are
|
|
returned during the enumeration process.
|
|
|
|
.. c:type:: media_links_enum
|
|
|
|
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
|
|
|
|
.. flat-table:: struct media_links_enum
|
|
:header-rows: 0
|
|
:stub-columns: 0
|
|
:widths: 1 1 2
|
|
|
|
* - __u32
|
|
- ``entity``
|
|
- Entity id, set by the application.
|
|
|
|
* - struct :c:type:`media_pad_desc`
|
|
- \*\ ``pads``
|
|
- Pointer to a pads array allocated by the application. Ignored if
|
|
NULL.
|
|
|
|
* - struct :c:type:`media_link_desc`
|
|
- \*\ ``links``
|
|
- Pointer to a links array allocated by the application. Ignored if
|
|
NULL.
|
|
|
|
* - __u32
|
|
- ``reserved[4]``
|
|
- Reserved for future extensions. Drivers and applications must set
|
|
the array to zero.
|
|
|
|
.. c:type:: media_pad_desc
|
|
|
|
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
|
|
|
|
.. flat-table:: struct media_pad_desc
|
|
:header-rows: 0
|
|
:stub-columns: 0
|
|
:widths: 1 1 2
|
|
|
|
* - __u32
|
|
- ``entity``
|
|
- ID of the entity this pad belongs to.
|
|
|
|
* - __u16
|
|
- ``index``
|
|
- Pad index, starts at 0.
|
|
|
|
* - __u32
|
|
- ``flags``
|
|
- Pad flags, see :ref:`media-pad-flag` for more details.
|
|
|
|
* - __u32
|
|
- ``reserved[2]``
|
|
- Reserved for future extensions. Drivers and applications must set
|
|
the array to zero.
|
|
|
|
|
|
.. c:type:: media_link_desc
|
|
|
|
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
|
|
|
|
.. flat-table:: struct media_link_desc
|
|
:header-rows: 0
|
|
:stub-columns: 0
|
|
:widths: 1 1 2
|
|
|
|
* - struct :c:type:`media_pad_desc`
|
|
- ``source``
|
|
- Pad at the origin of this link.
|
|
|
|
* - struct :c:type:`media_pad_desc`
|
|
- ``sink``
|
|
- Pad at the target of this link.
|
|
|
|
* - __u32
|
|
- ``flags``
|
|
- Link flags, see :ref:`media-link-flag` for more details.
|
|
|
|
* - __u32
|
|
- ``reserved[2]``
|
|
- Reserved for future extensions. Drivers and applications must set
|
|
the array to zero.
|
|
|
|
Return Value
|
|
============
|
|
|
|
On success 0 is returned, on error -1 and the ``errno`` variable is set
|
|
appropriately. The generic error codes are described at the
|
|
:ref:`Generic Error Codes <gen-errors>` chapter.
|
|
|
|
EINVAL
|
|
The struct :c:type:`media_links_enum` ``id``
|
|
references a non-existing entity.
|