blob: c81765f14b9f6aa97e3d4abd16a59893f790d527 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
|
.. -*- coding: utf-8; mode: rst -*-
.. _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:function:: int ioctl( int fd, MEDIA_IOC_ENUM_LINKS, struct media_links_enum *argp )
:name: MEDIA_IOC_ENUM_LINKS
Arguments
=========
``fd``
File descriptor returned by :ref:`open() <media-func-open>`.
``argp``
Description
===========
To enumerate pads and/or links for a given entity, applications set the
entity field of a struct :ref:`media_links_enum <media-links-enum>`
structure and initialize the struct
:ref:`media_pad_desc <media-pad-desc>` and struct
:ref:`media_link_desc <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.
.. _media-links-enum:
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
.. flat-table:: struct media_links_enum
:header-rows: 0
:stub-columns: 0
:widths: 1 1 2
- .. row 1
- __u32
- ``entity``
- Entity id, set by the application.
- .. row 2
- struct :ref:`media_pad_desc <media-pad-desc>`
- \*\ ``pads``
- Pointer to a pads array allocated by the application. Ignored if
NULL.
- .. row 3
- struct :ref:`media_link_desc <media-link-desc>`
- \*\ ``links``
- Pointer to a links array allocated by the application. Ignored if
NULL.
.. _media-pad-desc:
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
.. flat-table:: struct media_pad_desc
:header-rows: 0
:stub-columns: 0
:widths: 1 1 2
- .. row 1
- __u32
- ``entity``
- ID of the entity this pad belongs to.
- .. row 2
- __u16
- ``index``
- 0-based pad index.
- .. row 3
- __u32
- ``flags``
- Pad flags, see :ref:`media-pad-flag` for more details.
.. _media-link-desc:
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.7cm}|
.. flat-table:: struct media_link_desc
:header-rows: 0
:stub-columns: 0
:widths: 1 1 2
- .. row 1
- struct :ref:`media_pad_desc <media-pad-desc>`
- ``source``
- Pad at the origin of this link.
- .. row 2
- struct :ref:`media_pad_desc <media-pad-desc>`
- ``sink``
- Pad at the target of this link.
- .. row 3
- __u32
- ``flags``
- Link flags, see :ref:`media-link-flag` for more details.
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 :ref:`media_links_enum <media-links-enum>` ``id``
references a non-existing entity.
|
