1 .. -*- coding: utf-8; mode: rst -*-
3 .. _media_ioc_g_topology:
5 **************************
6 ioctl MEDIA_IOC_G_TOPOLOGY
7 **************************
12 MEDIA_IOC_G_TOPOLOGY - Enumerate the graph topology and graph element properties
18 .. c:function:: int ioctl( int fd, MEDIA_IOC_G_TOPOLOGY, struct media_v2_topology *argp )
19 :name: MEDIA_IOC_G_TOPOLOGY
26 File descriptor returned by :ref:`open() <media-func-open>`.
34 The typical usage of this ioctl is to call it twice. On the first call,
35 the structure defined at struct
36 :c:type:`media_v2_topology` should be zeroed. At
37 return, if no errors happen, this ioctl will return the
38 ``topology_version`` and the total number of entities, interfaces, pads
41 Before the second call, the userspace should allocate arrays to store
42 the graph elements that are desired, putting the pointers to them at the
43 ptr_entities, ptr_interfaces, ptr_links and/or ptr_pads, keeping the
44 other values untouched.
46 If the ``topology_version`` remains the same, the ioctl should fill the
47 desired arrays with the media graph elements.
49 .. tabularcolumns:: |p{1.6cm}|p{3.4cm}|p{12.5cm}|
51 .. c:type:: media_v2_topology
53 .. flat-table:: struct media_v2_topology
59 - ``topology_version``
60 - Version of the media graph topology. When the graph is created,
61 this field starts with zero. Every time a graph element is added
62 or removed, this field is incremented.
66 - Number of entities in the graph
70 - Applications and drivers shall set this to 0.
74 - A pointer to a memory area where the entities array will be
75 stored, converted to a 64-bits integer. It can be zero. if zero,
76 the ioctl won't store the entities. It will just update
81 - Number of interfaces in the graph
85 - Applications and drivers shall set this to 0.
89 - A pointer to a memory area where the interfaces array will be
90 stored, converted to a 64-bits integer. It can be zero. if zero,
91 the ioctl won't store the interfaces. It will just update
96 - Total number of pads in the graph
100 - Applications and drivers shall set this to 0.
104 - A pointer to a memory area where the pads array will be stored,
105 converted to a 64-bits integer. It can be zero. if zero, the ioctl
106 won't store the pads. It will just update ``num_pads``
110 - Total number of data and interface links in the graph
114 - Applications and drivers shall set this to 0.
118 - A pointer to a memory area where the links array will be stored,
119 converted to a 64-bits integer. It can be zero. if zero, the ioctl
120 won't store the links. It will just update ``num_links``
123 .. tabularcolumns:: |p{1.6cm}|p{3.2cm}|p{12.7cm}|
125 .. c:type:: media_v2_entity
127 .. flat-table:: struct media_v2_entity
134 - Unique ID for the entity. Do not expect that the ID will
135 always be the same for each instance of the device. In other words,
136 do not hardcode entity IDs in an application.
140 - Entity name as an UTF-8 NULL-terminated string. This name must be unique
141 within the media topology.
145 - Entity main function, see :ref:`media-entity-functions` for details.
149 - Entity flags, see :ref:`media-entity-flag` for details.
150 Only valid if ``MEDIA_V2_ENTITY_HAS_FLAGS(media_version)``
151 returns true. The ``media_version`` is defined in struct
152 :c:type:`media_device_info` and can be retrieved using
153 :ref:`MEDIA_IOC_DEVICE_INFO`.
157 - Reserved for future extensions. Drivers and applications must set
161 .. tabularcolumns:: |p{1.6cm}|p{3.2cm}|p{12.7cm}|
163 .. c:type:: media_v2_interface
165 .. flat-table:: struct media_v2_interface
172 - Unique ID for the interface. Do not expect that the ID will
173 always be the same for each instance of the device. In other words,
174 do not hardcode interface IDs in an application.
178 - Interface type, see :ref:`media-intf-type` for details.
182 - Interface flags. Currently unused.
186 - Reserved for future extensions. Drivers and applications must set
189 * - struct media_v2_intf_devnode
191 - Used only for device node interfaces. See
192 :c:type:`media_v2_intf_devnode` for details.
195 .. tabularcolumns:: |p{1.6cm}|p{3.2cm}|p{12.7cm}|
197 .. c:type:: media_v2_intf_devnode
199 .. flat-table:: struct media_v2_intf_devnode
206 - Device node major number.
210 - Device node minor number.
212 .. tabularcolumns:: |p{1.6cm}|p{3.2cm}|p{12.7cm}|
214 .. c:type:: media_v2_pad
216 .. flat-table:: struct media_v2_pad
223 - Unique ID for the pad. Do not expect that the ID will
224 always be the same for each instance of the device. In other words,
225 do not hardcode pad IDs in an application.
229 - Unique ID for the entity where this pad belongs.
233 - Pad flags, see :ref:`media-pad-flag` for more details.
237 - Pad index, starts at 0. Only valid if ``MEDIA_V2_PAD_HAS_INDEX(media_version)``
238 returns true. The ``media_version`` is defined in struct
239 :c:type:`media_device_info` and can be retrieved using
240 :ref:`MEDIA_IOC_DEVICE_INFO`.
244 - Reserved for future extensions. Drivers and applications must set
248 .. tabularcolumns:: |p{1.6cm}|p{3.2cm}|p{12.7cm}|
250 .. c:type:: media_v2_link
252 .. flat-table:: struct media_v2_link
259 - Unique ID for the link. Do not expect that the ID will
260 always be the same for each instance of the device. In other words,
261 do not hardcode link IDs in an application.
265 - On pad to pad links: unique ID for the source pad.
267 On interface to entity links: unique ID for the interface.
271 - On pad to pad links: unique ID for the sink pad.
273 On interface to entity links: unique ID for the entity.
277 - Link flags, see :ref:`media-link-flag` for more details.
281 - Reserved for future extensions. Drivers and applications must set
288 On success 0 is returned, on error -1 and the ``errno`` variable is set
289 appropriately. The generic error codes are described at the
290 :ref:`Generic Error Codes <gen-errors>` chapter.
293 This is returned when either one or more of the num_entities,
294 num_interfaces, num_links or num_pads are non-zero and are
295 smaller than the actual number of elements inside the graph. This
296 may happen if the ``topology_version`` changed when compared to the
297 last time this ioctl was called. Userspace should usually free the
298 area for the pointers, zero the struct elements and call this ioctl