[media] doc-rst: Fix conversion for MC core functions
There were lots of issues at the media controller side, after the conversion: - Some documentation at the header files weren't using the kernel-doc start block; - Now, the C files with the exported symbols also need to be added. So, all headers need to be included twice: one to get the structs/enums/.. and another one for the functions; - Notes should use the ReST tag, as kernel-doc doesn't recognizes it anymore; - Identation needs to be fixed, as ReST uses it to identify when a format "tag" ends. - Fix the cross-references at the media controller description. Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
This commit is contained in:
Mauro Carvalho Chehab
parent
89cb3ddbe7
commit
74604b7390
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@ -4,9 +4,8 @@ Media Controller devices
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Media Controller
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~~~~~~~~~~~~~~~~
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The media controller userspace API is documented in DocBook format in
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Documentation/DocBook/media/v4l/media-controller.xml. This document focus
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The media controller userspace API is documented in
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:ref:`the Media Controller uAPI book <media_common>`. This document focus
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on the kernel-side implementation of the media framework.
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Abstract media device model
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@ -35,72 +34,77 @@ pad to a sink pad.
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Media device
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^^^^^^^^^^^^
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A media device is represented by a struct &media_device instance, defined in
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include/media/media-device.h. Allocation of the structure is handled by the
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media device driver, usually by embedding the &media_device instance in a
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larger driver-specific structure.
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A media device is represented by a :c:type:`struct media_device <media_device>`
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instance, defined in ``include/media/media-device.h``.
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Allocation of the structure is handled by the media device driver, usually by
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embedding the :c:type:`media_device` instance in a larger driver-specific
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structure.
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Drivers register media device instances by calling
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__media_device_register() via the macro media_device_register()
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and unregistered by calling
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media_device_unregister().
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:cpp:func:`__media_device_register()` via the macro ``media_device_register()``
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and unregistered by calling :cpp:func:`media_device_unregister()`.
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Entities
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^^^^^^^^
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Entities are represented by a struct &media_entity instance, defined in
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include/media/media-entity.h. The structure is usually embedded into a
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higher-level structure, such as a v4l2_subdev or video_device instance,
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although drivers can allocate entities directly.
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Entities are represented by a :c:type:`struct media_entity <media_entity>`
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instance, defined in ``include/media/media-entity.h``. The structure is usually
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embedded into a higher-level structure, such as
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:ref:`v4l2_subdev` or :ref:`video_device`
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instances, although drivers can allocate entities directly.
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Drivers initialize entity pads by calling
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media_entity_pads_init().
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:cpp:func:`media_entity_pads_init()`.
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Drivers register entities with a media device by calling
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media_device_register_entity()
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:cpp:func:`media_device_register_entity()`
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and unregistred by calling
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media_device_unregister_entity().
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:cpp:func:`media_device_unregister_entity()`.
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Interfaces
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^^^^^^^^^^
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Interfaces are represented by a struct &media_interface instance, defined in
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include/media/media-entity.h. Currently, only one type of interface is
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defined: a device node. Such interfaces are represented by a struct
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&media_intf_devnode.
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Interfaces are represented by a
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:c:type:`struct media_interface <media_interface>` instance, defined in
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``include/media/media-entity.h``. Currently, only one type of interface is
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defined: a device node. Such interfaces are represented by a
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:c:type:`struct media_intf_devnode <media_intf_devnode>`.
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Drivers initialize and create device node interfaces by calling
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media_devnode_create()
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:cpp:func:`media_devnode_create()`
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and remove them by calling:
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media_devnode_remove().
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:cpp:func:`media_devnode_remove()`.
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Pads
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^^^^
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Pads are represented by a struct &media_pad instance, defined in
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include/media/media-entity.h. Each entity stores its pads in a pads array
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managed by the entity driver. Drivers usually embed the array in a
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driver-specific structure.
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Pads are represented by a :c:type:`struct media_pad <media_pad>` instance,
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defined in ``include/media/media-entity.h``. Each entity stores its pads in
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a pads array managed by the entity driver. Drivers usually embed the array in
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a driver-specific structure.
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Pads are identified by their entity and their 0-based index in the pads
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array.
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Both information are stored in the &media_pad structure, making the
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&media_pad pointer the canonical way to store and pass link references.
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Both information are stored in the :c:type:`struct media_pad`, making the
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:c:type:`media_pad` pointer the canonical way to store and pass link references.
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Pads have flags that describe the pad capabilities and state.
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%MEDIA_PAD_FL_SINK indicates that the pad supports sinking data.
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%MEDIA_PAD_FL_SOURCE indicates that the pad supports sourcing data.
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``MEDIA_PAD_FL_SINK`` indicates that the pad supports sinking data.
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``MEDIA_PAD_FL_SOURCE`` indicates that the pad supports sourcing data.
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NOTE: One and only one of %MEDIA_PAD_FL_SINK and %MEDIA_PAD_FL_SOURCE must
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be set for each pad.
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.. note::
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One and only one of ``MEDIA_PAD_FL_SINK`` or ``MEDIA_PAD_FL_SOURCE`` must
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be set for each pad.
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Links
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^^^^^
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Links are represented by a struct &media_link instance, defined in
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include/media/media-entity.h. There are two types of links:
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Links are represented by a :c:type:`struct media_link <media_link>` instance,
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defined in ``include/media/media-entity.h``. There are two types of links:
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1. pad to pad links:
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**1. pad to pad links**:
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Associate two entities via their PADs. Each entity has a list that points
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to all links originating at or targeting any of its pads.
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@ -108,22 +112,24 @@ A given link is thus stored twice, once in the source entity and once in
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the target entity.
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Drivers create pad to pad links by calling:
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media_create_pad_link() and remove with media_entity_remove_links().
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:cpp:func:`media_create_pad_link()` and remove with
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:cpp:func:`media_entity_remove_links()`.
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2. interface to entity links:
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**2. interface to entity links**:
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Associate one interface to a Link.
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Drivers create interface to entity links by calling:
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media_create_intf_link() and remove with media_remove_intf_links().
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:cpp:func:`media_create_intf_link()` and remove with
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:cpp:func:`media_remove_intf_links()`.
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.. note::
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Links can only be created after having both ends already created.
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Links have flags that describe the link capabilities and state. The
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valid values are described at media_create_pad_link() and
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media_create_intf_link().
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valid values are described at :cpp:func:`media_create_pad_link()` and
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:cpp:func:`media_create_intf_link()`.
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Graph traversal
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^^^^^^^^^^^^^^^
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@ -132,92 +138,103 @@ The media framework provides APIs to iterate over entities in a graph.
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To iterate over all entities belonging to a media device, drivers can use
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the media_device_for_each_entity macro, defined in
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include/media/media-device.h.
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``include/media/media-device.h``.
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struct media_entity *entity;
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.. code-block:: c
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media_device_for_each_entity(entity, mdev) {
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// entity will point to each entity in turn
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...
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}
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struct media_entity *entity;
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media_device_for_each_entity(entity, mdev) {
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// entity will point to each entity in turn
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...
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}
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Drivers might also need to iterate over all entities in a graph that can be
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reached only through enabled links starting at a given entity. The media
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framework provides a depth-first graph traversal API for that purpose.
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Note that graphs with cycles (whether directed or undirected) are *NOT*
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supported by the graph traversal API. To prevent infinite loops, the graph
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traversal code limits the maximum depth to MEDIA_ENTITY_ENUM_MAX_DEPTH,
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currently defined as 16.
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.. note::
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Graphs with cycles (whether directed or undirected) are **NOT**
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supported by the graph traversal API. To prevent infinite loops, the graph
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traversal code limits the maximum depth to ``MEDIA_ENTITY_ENUM_MAX_DEPTH``,
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currently defined as 16.
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Drivers initiate a graph traversal by calling
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media_entity_graph_walk_start()
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:cpp:func:`media_entity_graph_walk_start()`
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The graph structure, provided by the caller, is initialized to start graph
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traversal at the given entity.
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Drivers can then retrieve the next entity by calling
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media_entity_graph_walk_next()
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:cpp:func:`media_entity_graph_walk_next()`
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When the graph traversal is complete the function will return NULL.
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When the graph traversal is complete the function will return ``NULL``.
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Graph traversal can be interrupted at any moment. No cleanup function call
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is required and the graph structure can be freed normally.
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Helper functions can be used to find a link between two given pads, or a pad
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connected to another pad through an enabled link
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media_entity_find_link() and media_entity_remote_pad()
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:cpp:func:`media_entity_find_link()` and
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:cpp:func:`media_entity_remote_pad()`.
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Use count and power handling
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Due to the wide differences between drivers regarding power management
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needs, the media controller does not implement power management. However,
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the &media_entity structure includes a use_count field that media drivers
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the :c:type:`struct media_entity <media_entity>` includes a ``use_count``
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field that media drivers
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can use to track the number of users of every entity for power management
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needs.
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The &media_entity.@use_count field is owned by media drivers and must not be
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The :c:type:`media_entity<media_entity>`.\ ``use_count`` field is owned by
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media drivers and must not be
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touched by entity drivers. Access to the field must be protected by the
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&media_device.@graph_mutex lock.
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:c:type:`media_device`.\ ``graph_mutex`` lock.
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Links setup
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^^^^^^^^^^^
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Link properties can be modified at runtime by calling
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media_entity_setup_link()
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:cpp:func:`media_entity_setup_link()`.
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Pipelines and media streams
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^^^^^^^^^^^^^^^^^^^^^^^^^^^
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When starting streaming, drivers must notify all entities in the pipeline to
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prevent link states from being modified during streaming by calling
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media_entity_pipeline_start().
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:cpp:func:`media_entity_pipeline_start()`.
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The function will mark all entities connected to the given entity through
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enabled links, either directly or indirectly, as streaming.
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The &media_pipeline instance pointed to by the pipe argument will be stored
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in every entity in the pipeline. Drivers should embed the &media_pipeline
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structure in higher-level pipeline structures and can then access the
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pipeline through the &media_entity pipe field.
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The :c:type:`struct media_pipeline <media_pipeline>` instance pointed to by
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the pipe argument will be stored in every entity in the pipeline.
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Drivers should embed the :c:type:`struct media_pipeline <media_pipeline>`
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in higher-level pipeline structures and can then access the
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pipeline through the :c:type:`struct media_entity <media_entity>`
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pipe field.
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Calls to media_entity_pipeline_start() can be nested. The pipeline pointer
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must be identical for all nested calls to the function.
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Calls to :cpp:func:`media_entity_pipeline_start()` can be nested.
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The pipeline pointer must be identical for all nested calls to the function.
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media_entity_pipeline_start() may return an error. In that case, it will
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clean up any of the changes it did by itself.
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:cpp:func:`media_entity_pipeline_start()` may return an error. In that case,
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it will clean up any of the changes it did by itself.
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When stopping the stream, drivers must notify the entities with
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media_entity_pipeline_stop().
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:cpp:func:`media_entity_pipeline_stop()`.
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If multiple calls to media_entity_pipeline_start() have been made the same
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number of media_entity_pipeline_stop() calls are required to stop streaming.
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The &media_entity pipe field is reset to NULL on the last nested stop call.
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If multiple calls to :cpp:func:`media_entity_pipeline_start()` have been
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made the same number of :cpp:func:`media_entity_pipeline_stop()` calls
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are required to stop streaming.
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The :c:type:`media_entity`.\ ``pipe`` field is reset to ``NULL`` on the last
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nested stop call.
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Link configuration will fail with -%EBUSY by default if either end of the
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Link configuration will fail with ``-EBUSY`` by default if either end of the
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link is a streaming entity. Links that can be modified while streaming must
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be marked with the %MEDIA_LNK_FL_DYNAMIC flag.
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be marked with the ``MEDIA_LNK_FL_DYNAMIC`` flag.
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If other operations need to be disallowed on streaming entities (such as
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changing entities configuration parameters) drivers can explicitly check the
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@ -227,13 +244,13 @@ operation must be done with the media_device graph_mutex held.
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Link validation
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^^^^^^^^^^^^^^^
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Link validation is performed by media_entity_pipeline_start() for any
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entity which has sink pads in the pipeline. The
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&media_entity.@link_validate() callback is used for that purpose. In
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@link_validate() callback, entity driver should check that the properties of
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the source pad of the connected entity and its own sink pad match. It is up
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to the type of the entity (and in the end, the properties of the hardware)
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what matching actually means.
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Link validation is performed by :cpp:func:`media_entity_pipeline_start()`
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for any entity which has sink pads in the pipeline. The
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:c:type:`media_entity`.\ ``link_validate()`` callback is used for that
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purpose. In ``link_validate()`` callback, entity driver should check
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that the properties of the source pad of the connected entity and its own
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sink pad match. It is up to the type of the entity (and in the end, the
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properties of the hardware) what matching actually means.
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Subsystems should facilitate link validation by providing subsystem specific
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helper functions to provide easy access for commonly needed information, and
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@ -245,3 +262,10 @@ in the end provide a way to use driver-specific callbacks.
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.. kernel-doc:: include/media/media-entity.h
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.. kernel-doc:: include/media/media-device.h
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:export: drivers/media/media-device.c
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.. kernel-doc:: include/media/media-entity.h
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:export: drivers/media/media-entity.c
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@ -242,13 +242,11 @@ void media_device_cleanup(struct media_device *mdev);
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* without breaking binary compatibility. The version major must be
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* incremented when binary compatibility is broken.
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*
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* Notes:
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* .. note::
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*
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* Upon successful registration a character device named media[0-9]+ is created.
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* The device major and minor numbers are dynamic. The model name is exported as
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* a sysfs attribute.
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* #) Upon successful registration a character device named media[0-9]+ is created. The device major and minor numbers are dynamic. The model name is exported as a sysfs attribute.
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*
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* Unregistering a media device that hasn't been registered is *NOT* safe.
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* #) Unregistering a media device that hasn't been registered is **NOT** safe.
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*
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* Return: returns zero on success or a negative error code.
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*/
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@ -296,14 +294,16 @@ void media_device_unregister(struct media_device *mdev);
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* This can be used to report the default audio and video devices or the
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* default camera sensor.
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*
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* NOTE: Drivers should set the entity function before calling this function.
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* Please notice that the values %MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN and
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* %MEDIA_ENT_F_UNKNOWN should not be used by the drivers.
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* .. note::
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*
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* Drivers should set the entity function before calling this function.
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* Please notice that the values %MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN and
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* %MEDIA_ENT_F_UNKNOWN should not be used by the drivers.
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*/
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int __must_check media_device_register_entity(struct media_device *mdev,
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struct media_entity *entity);
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/*
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/**
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* media_device_unregister_entity() - unregisters a media entity.
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*
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* @entity: pointer to struct &media_entity to be unregistered
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@ -317,8 +317,10 @@ int __must_check media_device_register_entity(struct media_device *mdev,
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* When a media device is unregistered, all its entities are unregistered
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* automatically. No manual entities unregistration is then required.
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*
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* Note: the media_entity instance itself must be freed explicitly by
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* the driver if required.
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* .. note::
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*
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* The media_entity instance itself must be freed explicitly by
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* the driver if required.
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*/
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void media_device_unregister_entity(struct media_entity *entity);
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@ -104,7 +104,7 @@ struct media_entity_graph {
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int top;
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};
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/*
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/**
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* struct media_pipeline - Media pipeline related information
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*
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* @streaming_count: Streaming start count - streaming stop count
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@ -180,7 +180,7 @@ struct media_pad {
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* view. The media_entity_pipeline_start() function
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* validates all links by calling this operation. Optional.
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*
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* Note: Those these callbacks are called with struct media_device.@graph_mutex
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* .. note:: Those these callbacks are called with struct media_device.@graph_mutex
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* mutex held.
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*/
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struct media_entity_operations {
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@ -602,19 +602,20 @@ static inline void media_entity_cleanup(struct media_entity *entity) {};
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* @flags: Link flags, as defined in include/uapi/linux/media.h.
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*
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* Valid values for flags:
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* A %MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can be
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* used to transfer media data. When two or more links target a sink pad,
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* only one of them can be enabled at a time.
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*
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* A %MEDIA_LNK_FL_IMMUTABLE flag indicates that the link enabled state can't
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* be modified at runtime. If %MEDIA_LNK_FL_IMMUTABLE is set, then
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* %MEDIA_LNK_FL_ENABLED must also be set since an immutable link is
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* always enabled.
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* - A %MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can
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* be used to transfer media data. When two or more links target a sink pad,
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* only one of them can be enabled at a time.
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*
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* NOTE:
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* - A %MEDIA_LNK_FL_IMMUTABLE flag indicates that the link enabled state can't
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* be modified at runtime. If %MEDIA_LNK_FL_IMMUTABLE is set, then
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* %MEDIA_LNK_FL_ENABLED must also be set since an immutable link is
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* always enabled.
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*
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* Before calling this function, media_entity_pads_init() and
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* media_device_register_entity() should be called previously for both ends.
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* .. note::
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*
|
||||
* Before calling this function, media_entity_pads_init() and
|
||||
* media_device_register_entity() should be called previously for both ends.
|
||||
*/
|
||||
__must_check int media_create_pad_link(struct media_entity *source,
|
||||
u16 source_pad, struct media_entity *sink,
|
||||
|
|
@ -641,6 +642,7 @@ __must_check int media_create_pad_link(struct media_entity *source,
|
|||
* and @sink are NULL.
|
||||
*
|
||||
* Valid values for flags:
|
||||
*
|
||||
* A %MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can be
|
||||
* used to transfer media data. If multiple links are created and this
|
||||
* flag is passed as an argument, only the first created link will have
|
||||
|
|
@ -677,8 +679,10 @@ void __media_entity_remove_links(struct media_entity *entity);
|
|||
*
|
||||
* @entity: pointer to &media_entity
|
||||
*
|
||||
* Note: this is called automatically when an entity is unregistered via
|
||||
* media_device_register_entity().
|
||||
* .. note::
|
||||
*
|
||||
* This is called automatically when an entity is unregistered via
|
||||
* media_device_register_entity().
|
||||
*/
|
||||
void media_entity_remove_links(struct media_entity *entity);
|
||||
|
||||
|
|
@ -728,9 +732,11 @@ int __media_entity_setup_link(struct media_link *link, u32 flags);
|
|||
* being enabled, the link_setup operation must return -EBUSY and can't
|
||||
* implicitly disable the first enabled link.
|
||||
*
|
||||
* NOTE: the valid values of the flags for the link is the same as described
|
||||
* on media_create_pad_link(), for pad to pad links or the same as described
|
||||
* on media_create_intf_link(), for interface to entity links.
|
||||
* .. note::
|
||||
*
|
||||
* The valid values of the flags for the link is the same as described
|
||||
* on media_create_pad_link(), for pad to pad links or the same as described
|
||||
* on media_create_intf_link(), for interface to entity links.
|
||||
*/
|
||||
int media_entity_setup_link(struct media_link *link, u32 flags);
|
||||
|
||||
|
|
@ -844,7 +850,7 @@ __must_check int media_entity_pipeline_start(struct media_entity *entity,
|
|||
* @entity: Starting entity
|
||||
* @pipe: Media pipeline to be assigned to all entities in the pipeline.
|
||||
*
|
||||
* Note: This is the non-locking version of media_entity_pipeline_start()
|
||||
* ..note:: This is the non-locking version of media_entity_pipeline_start()
|
||||
*/
|
||||
__must_check int __media_entity_pipeline_start(struct media_entity *entity,
|
||||
struct media_pipeline *pipe);
|
||||
|
|
@ -868,7 +874,7 @@ void media_entity_pipeline_stop(struct media_entity *entity);
|
|||
*
|
||||
* @entity: Starting entity
|
||||
*
|
||||
* Note: This is the non-locking version of media_entity_pipeline_stop()
|
||||
* .. note:: This is the non-locking version of media_entity_pipeline_stop()
|
||||
*/
|
||||
void __media_entity_pipeline_stop(struct media_entity *entity);
|
||||
|
||||
|
|
@ -909,20 +915,21 @@ struct media_link *
|
|||
*
|
||||
*
|
||||
* Valid values for flags:
|
||||
* The %MEDIA_LNK_FL_ENABLED flag indicates that the interface is connected to
|
||||
* the entity hardware. That's the default value for interfaces. An
|
||||
* interface may be disabled if the hardware is busy due to the usage
|
||||
* of some other interface that it is currently controlling the hardware.
|
||||
* A typical example is an hybrid TV device that handle only one type of
|
||||
* stream on a given time. So, when the digital TV is streaming,
|
||||
* the V4L2 interfaces won't be enabled, as such device is not able to
|
||||
* also stream analog TV or radio.
|
||||
*
|
||||
* Note:
|
||||
* - The %MEDIA_LNK_FL_ENABLED flag indicates that the interface is connected to
|
||||
* the entity hardware. That's the default value for interfaces. An
|
||||
* interface may be disabled if the hardware is busy due to the usage
|
||||
* of some other interface that it is currently controlling the hardware.
|
||||
* A typical example is an hybrid TV device that handle only one type of
|
||||
* stream on a given time. So, when the digital TV is streaming,
|
||||
* the V4L2 interfaces won't be enabled, as such device is not able to
|
||||
* also stream analog TV or radio.
|
||||
*
|
||||
* Before calling this function, media_devnode_create() should be called for
|
||||
* the interface and media_device_register_entity() should be called for the
|
||||
* interface that will be part of the link.
|
||||
* .. note::
|
||||
*
|
||||
* Before calling this function, media_devnode_create() should be called for
|
||||
* the interface and media_device_register_entity() should be called for the
|
||||
* interface that will be part of the link.
|
||||
*/
|
||||
__must_check media_create_intf_link(struct media_entity *entity,
|
||||
struct media_interface *intf,
|
||||
|
|
@ -932,7 +939,7 @@ __must_check media_create_intf_link(struct media_entity *entity,
|
|||
*
|
||||
* @link: pointer to &media_link.
|
||||
*
|
||||
* Note: this is an unlocked version of media_remove_intf_link()
|
||||
* .. note:: This is an unlocked version of media_remove_intf_link()
|
||||
*/
|
||||
void __media_remove_intf_link(struct media_link *link);
|
||||
|
||||
|
|
@ -941,7 +948,7 @@ void __media_remove_intf_link(struct media_link *link);
|
|||
*
|
||||
* @link: pointer to &media_link.
|
||||
*
|
||||
* Note: prefer to use this one, instead of __media_remove_intf_link()
|
||||
* .. note:: Prefer to use this one, instead of __media_remove_intf_link()
|
||||
*/
|
||||
void media_remove_intf_link(struct media_link *link);
|
||||
|
||||
|
|
@ -950,7 +957,7 @@ void media_remove_intf_link(struct media_link *link);
|
|||
*
|
||||
* @intf: pointer to &media_interface
|
||||
*
|
||||
* Note: this is an unlocked version of media_remove_intf_links().
|
||||
* .. note:: This is an unlocked version of media_remove_intf_links().
|
||||
*/
|
||||
void __media_remove_intf_links(struct media_interface *intf);
|
||||
|
||||
|
|
@ -959,12 +966,12 @@ void __media_remove_intf_links(struct media_interface *intf);
|
|||
*
|
||||
* @intf: pointer to &media_interface
|
||||
*
|
||||
* Notes:
|
||||
* ..note::
|
||||
*
|
||||
* this is called automatically when an entity is unregistered via
|
||||
* media_device_register_entity() and by media_devnode_remove().
|
||||
* - This is called automatically when an entity is unregistered via
|
||||
* media_device_register_entity() and by media_devnode_remove().
|
||||
*
|
||||
* Prefer to use this one, instead of __media_remove_intf_links().
|
||||
* - Prefer to use this one, instead of __media_remove_intf_links().
|
||||
*/
|
||||
void media_remove_intf_links(struct media_interface *intf);
|
||||
|
||||
|
|
|
|||
Loading…
Reference in New Issue