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author | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2016-07-08 16:40:06 +0200 |
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committer | Mauro Carvalho Chehab <mchehab@s-opensource.com> | 2016-07-08 16:59:40 +0200 |
commit | 60c2820d0f6d3497975b6488e2599f8f611d8b95 (patch) | |
tree | b3b03707c6438ea9b99cc57e847ebf517f968ab1 /Documentation/media/uapi/mediactl/media-ioc-g-topology.rst | |
parent | doc-rst: remove an invalid include from the docs (diff) | |
download | linux-60c2820d0f6d3497975b6488e2599f8f611d8b95.tar.xz linux-60c2820d0f6d3497975b6488e2599f8f611d8b95.zip |
doc_rst: rename the media Sphinx suff to Documentation/media
The name of the subsystem is "media", and not "linux_tv". Also,
as we plan to add other stuff there in the future, let's
rename also the media uAPI book to media_uapi, to make it
clearer.
No functional changes.
Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
Diffstat (limited to 'Documentation/media/uapi/mediactl/media-ioc-g-topology.rst')
-rw-r--r-- | Documentation/media/uapi/mediactl/media-ioc-g-topology.rst | 377 |
1 files changed, 377 insertions, 0 deletions
diff --git a/Documentation/media/uapi/mediactl/media-ioc-g-topology.rst b/Documentation/media/uapi/mediactl/media-ioc-g-topology.rst new file mode 100644 index 000000000000..1f2d530aa284 --- /dev/null +++ b/Documentation/media/uapi/mediactl/media-ioc-g-topology.rst @@ -0,0 +1,377 @@ +.. -*- coding: utf-8; mode: rst -*- + +.. _media-g-topology: + +************************** +ioctl MEDIA_IOC_G_TOPOLOGY +************************** + +Name +==== + +MEDIA_IOC_G_TOPOLOGY - Enumerate the graph topology and graph element properties + + +Synopsis +======== + +.. cpp:function:: int ioctl( int fd, int request, struct media_v2_topology *argp ) + + +Arguments +========= + +``fd`` + File descriptor returned by :ref:`open() <media-func-open>`. + +``request`` + MEDIA_IOC_G_TOPOLOGY + +``argp`` + + +Description +=========== + +The typical usage of this ioctl is to call it twice. On the first call, +the structure defined at struct +:ref:`media_v2_topology <media-v2-topology>` should be zeroed. At +return, if no errors happen, this ioctl will return the +``topology_version`` and the total number of entities, interfaces, pads +and links. + +Before the second call, the userspace should allocate arrays to store +the graph elements that are desired, putting the pointers to them at the +ptr_entities, ptr_interfaces, ptr_links and/or ptr_pads, keeping the +other values untouched. + +If the ``topology_version`` remains the same, the ioctl should fill the +desired arrays with the media graph elements. + + +.. _media-v2-topology: + +.. flat-table:: struct media_v2_topology + :header-rows: 0 + :stub-columns: 0 + :widths: 1 2 8 + + + - .. row 1 + + - __u64 + + - ``topology_version`` + + - Version of the media graph topology. When the graph is created, + this field starts with zero. Every time a graph element is added + or removed, this field is incremented. + + - .. row 2 + + - __u64 + + - ``num_entities`` + + - Number of entities in the graph + + - .. row 3 + + - __u64 + + - ``ptr_entities`` + + - A pointer to a memory area where the entities array will be + stored, converted to a 64-bits integer. It can be zero. if zero, + the ioctl won't store the entities. It will just update + ``num_entities`` + + - .. row 4 + + - __u64 + + - ``num_interfaces`` + + - Number of interfaces in the graph + + - .. row 5 + + - __u64 + + - ``ptr_interfaces`` + + - A pointer to a memory area where the interfaces array will be + stored, converted to a 64-bits integer. It can be zero. if zero, + the ioctl won't store the interfaces. It will just update + ``num_interfaces`` + + - .. row 6 + + - __u64 + + - ``num_pads`` + + - Total number of pads in the graph + + - .. row 7 + + - __u64 + + - ``ptr_pads`` + + - A pointer to a memory area where the pads array will be stored, + converted to a 64-bits integer. It can be zero. if zero, the ioctl + won't store the pads. It will just update ``num_pads`` + + - .. row 8 + + - __u64 + + - ``num_links`` + + - Total number of data and interface links in the graph + + - .. row 9 + + - __u64 + + - ``ptr_links`` + + - A pointer to a memory area where the links array will be stored, + converted to a 64-bits integer. It can be zero. if zero, the ioctl + won't store the links. It will just update ``num_links`` + + + +.. _media-v2-entity: + +.. flat-table:: struct media_v2_entity + :header-rows: 0 + :stub-columns: 0 + :widths: 1 2 8 + + + - .. row 1 + + - __u32 + + - ``id`` + + - Unique ID for the entity. + + - .. row 2 + + - char + + - ``name``\ [64] + + - Entity name as an UTF-8 NULL-terminated string. + + - .. row 3 + + - __u32 + + - ``function`` + + - Entity main function, see :ref:`media-entity-type` for details. + + - .. row 4 + + - __u32 + + - ``reserved``\ [12] + + - Reserved for future extensions. Drivers and applications must set + this array to zero. + + + +.. _media-v2-interface: + +.. flat-table:: struct media_v2_interface + :header-rows: 0 + :stub-columns: 0 + :widths: 1 2 8 + + - .. row 1 + + - __u32 + + - ``id`` + + - Unique ID for the interface. + + - .. row 2 + + - __u32 + + - ``intf_type`` + + - Interface type, see :ref:`media-intf-type` for details. + + - .. row 3 + + - __u32 + + - ``flags`` + + - Interface flags. Currently unused. + + - .. row 4 + + - __u32 + + - ``reserved``\ [9] + + - Reserved for future extensions. Drivers and applications must set + this array to zero. + + - .. row 5 + + - struct media_v2_intf_devnode + + - ``devnode`` + + - Used only for device node interfaces. See + :ref:`media-v2-intf-devnode` for details.. + + + +.. _media-v2-intf-devnode: + +.. flat-table:: struct media_v2_interface + :header-rows: 0 + :stub-columns: 0 + :widths: 1 2 8 + + + - .. row 1 + + - __u32 + + - ``major`` + + - Device node major number. + + - .. row 2 + + - __u32 + + - ``minor`` + + - Device node minor number. + + + +.. _media-v2-pad: + +.. flat-table:: struct media_v2_pad + :header-rows: 0 + :stub-columns: 0 + :widths: 1 2 8 + + + - .. row 1 + + - __u32 + + - ``id`` + + - Unique ID for the pad. + + - .. row 2 + + - __u32 + + - ``entity_id`` + + - Unique ID for the entity where this pad belongs. + + - .. row 3 + + - __u32 + + - ``flags`` + + - Pad flags, see :ref:`media-pad-flag` for more details. + + - .. row 4 + + - __u32 + + - ``reserved``\ [9] + + - Reserved for future extensions. Drivers and applications must set + this array to zero. + + + +.. _media-v2-link: + +.. flat-table:: struct media_v2_pad + :header-rows: 0 + :stub-columns: 0 + :widths: 1 2 8 + + + - .. row 1 + + - __u32 + + - ``id`` + + - Unique ID for the pad. + + - .. row 2 + + - __u32 + + - ``source_id`` + + - On pad to pad links: unique ID for the source pad. + + On interface to entity links: unique ID for the interface. + + - .. row 3 + + - __u32 + + - ``sink_id`` + + - On pad to pad links: unique ID for the sink pad. + + On interface to entity links: unique ID for the entity. + + - .. row 4 + + - __u32 + + - ``flags`` + + - Link flags, see :ref:`media-link-flag` for more details. + + - .. row 5 + + - __u32 + + - ``reserved``\ [5] + + - Reserved for future extensions. Drivers and applications must set + this 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. + +ENOSPC + This is returned when either one or more of the num_entities, + num_interfaces, num_links or num_pads are non-zero and are + smaller than the actual number of elements inside the graph. This + may happen if the ``topology_version`` changed when compared to the + last time this ioctl was called. Userspace should usually free the + area for the pointers, zero the struct elements and call this ioctl + again. |