[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 2016-07-17 09:18:03 -03:00
parent 89cb3ddbe7
commit 74604b7390
3 changed files with 163 additions and 130 deletions

View File

@ -4,9 +4,8 @@ Media Controller devices
Media Controller
~~~~~~~~~~~~~~~~
The media controller userspace API is documented in DocBook format in
Documentation/DocBook/media/v4l/media-controller.xml. This document focus
The media controller userspace API is documented in
:ref:`the Media Controller uAPI book <media_common>`. This document focus
on the kernel-side implementation of the media framework.
Abstract media device model
@ -35,72 +34,77 @@ pad to a sink pad.
Media device
^^^^^^^^^^^^
A media device is represented by a struct &media_device instance, defined in
include/media/media-device.h. Allocation of the structure is handled by the
media device driver, usually by embedding the &media_device instance in a
larger driver-specific structure.
A media device is represented by a :c:type:`struct media_device <media_device>`
instance, defined in ``include/media/media-device.h``.
Allocation of the structure is handled by the media device driver, usually by
embedding the :c:type:`media_device` instance in a larger driver-specific
structure.
Drivers register media device instances by calling
__media_device_register() via the macro media_device_register()
and unregistered by calling
media_device_unregister().
:cpp:func:`__media_device_register()` via the macro ``media_device_register()``
and unregistered by calling :cpp:func:`media_device_unregister()`.
Entities
^^^^^^^^
Entities are represented by a struct &media_entity instance, defined in
include/media/media-entity.h. The structure is usually embedded into a
higher-level structure, such as a v4l2_subdev or video_device instance,
although drivers can allocate entities directly.
Entities are represented by a :c:type:`struct media_entity <media_entity>`
instance, defined in ``include/media/media-entity.h``. The structure is usually
embedded into a higher-level structure, such as
:ref:`v4l2_subdev` or :ref:`video_device`
instances, although drivers can allocate entities directly.
Drivers initialize entity pads by calling
media_entity_pads_init().
:cpp:func:`media_entity_pads_init()`.
Drivers register entities with a media device by calling
media_device_register_entity()
:cpp:func:`media_device_register_entity()`
and unregistred by calling
media_device_unregister_entity().
:cpp:func:`media_device_unregister_entity()`.
Interfaces
^^^^^^^^^^
Interfaces are represented by a struct &media_interface instance, defined in
include/media/media-entity.h. Currently, only one type of interface is
defined: a device node. Such interfaces are represented by a struct
&media_intf_devnode.
Interfaces are represented by a
:c:type:`struct media_interface <media_interface>` instance, defined in
``include/media/media-entity.h``. Currently, only one type of interface is
defined: a device node. Such interfaces are represented by a
:c:type:`struct media_intf_devnode <media_intf_devnode>`.
Drivers initialize and create device node interfaces by calling
media_devnode_create()
:cpp:func:`media_devnode_create()`
and remove them by calling:
media_devnode_remove().
:cpp:func:`media_devnode_remove()`.
Pads
^^^^
Pads are represented by a struct &media_pad instance, defined in
include/media/media-entity.h. Each entity stores its pads in a pads array
managed by the entity driver. Drivers usually embed the array in a
driver-specific structure.
Pads are represented by a :c:type:`struct media_pad <media_pad>` instance,
defined in ``include/media/media-entity.h``. Each entity stores its pads in
a pads array managed by the entity driver. Drivers usually embed the array in
a driver-specific structure.
Pads are identified by their entity and their 0-based index in the pads
array.
Both information are stored in the &media_pad structure, making the
&media_pad pointer the canonical way to store and pass link references.
Both information are stored in the :c:type:`struct media_pad`, making the
:c:type:`media_pad` pointer the canonical way to store and pass link references.
Pads have flags that describe the pad capabilities and state.
%MEDIA_PAD_FL_SINK indicates that the pad supports sinking data.
%MEDIA_PAD_FL_SOURCE indicates that the pad supports sourcing data.
``MEDIA_PAD_FL_SINK`` indicates that the pad supports sinking data.
``MEDIA_PAD_FL_SOURCE`` indicates that the pad supports sourcing data.
NOTE: One and only one of %MEDIA_PAD_FL_SINK and %MEDIA_PAD_FL_SOURCE must
.. note::
One and only one of ``MEDIA_PAD_FL_SINK`` or ``MEDIA_PAD_FL_SOURCE`` must
be set for each pad.
Links
^^^^^
Links are represented by a struct &media_link instance, defined in
include/media/media-entity.h. There are two types of links:
Links are represented by a :c:type:`struct media_link <media_link>` instance,
defined in ``include/media/media-entity.h``. There are two types of links:
1. pad to pad links:
**1. pad to pad links**:
Associate two entities via their PADs. Each entity has a list that points
to all links originating at or targeting any of its pads.
@ -108,22 +112,24 @@ A given link is thus stored twice, once in the source entity and once in
the target entity.
Drivers create pad to pad links by calling:
media_create_pad_link() and remove with media_entity_remove_links().
:cpp:func:`media_create_pad_link()` and remove with
:cpp:func:`media_entity_remove_links()`.
2. interface to entity links:
**2. interface to entity links**:
Associate one interface to a Link.
Drivers create interface to entity links by calling:
media_create_intf_link() and remove with media_remove_intf_links().
:cpp:func:`media_create_intf_link()` and remove with
:cpp:func:`media_remove_intf_links()`.
.. note::
Links can only be created after having both ends already created.
Links have flags that describe the link capabilities and state. The
valid values are described at media_create_pad_link() and
media_create_intf_link().
valid values are described at :cpp:func:`media_create_pad_link()` and
:cpp:func:`media_create_intf_link()`.
Graph traversal
^^^^^^^^^^^^^^^
@ -132,7 +138,9 @@ The media framework provides APIs to iterate over entities in a graph.
To iterate over all entities belonging to a media device, drivers can use
the media_device_for_each_entity macro, defined in
include/media/media-device.h.
``include/media/media-device.h``.
.. code-block:: c
struct media_entity *entity;
@ -145,79 +153,88 @@ Drivers might also need to iterate over all entities in a graph that can be
reached only through enabled links starting at a given entity. The media
framework provides a depth-first graph traversal API for that purpose.
Note that graphs with cycles (whether directed or undirected) are *NOT*
.. note::
Graphs with cycles (whether directed or undirected) are **NOT**
supported by the graph traversal API. To prevent infinite loops, the graph
traversal code limits the maximum depth to MEDIA_ENTITY_ENUM_MAX_DEPTH,
traversal code limits the maximum depth to ``MEDIA_ENTITY_ENUM_MAX_DEPTH``,
currently defined as 16.
Drivers initiate a graph traversal by calling
media_entity_graph_walk_start()
:cpp:func:`media_entity_graph_walk_start()`
The graph structure, provided by the caller, is initialized to start graph
traversal at the given entity.
Drivers can then retrieve the next entity by calling
media_entity_graph_walk_next()
:cpp:func:`media_entity_graph_walk_next()`
When the graph traversal is complete the function will return NULL.
When the graph traversal is complete the function will return ``NULL``.
Graph traversal can be interrupted at any moment. No cleanup function call
is required and the graph structure can be freed normally.
Helper functions can be used to find a link between two given pads, or a pad
connected to another pad through an enabled link
media_entity_find_link() and media_entity_remote_pad()
:cpp:func:`media_entity_find_link()` and
:cpp:func:`media_entity_remote_pad()`.
Use count and power handling
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Due to the wide differences between drivers regarding power management
needs, the media controller does not implement power management. However,
the &media_entity structure includes a use_count field that media drivers
the :c:type:`struct media_entity <media_entity>` includes a ``use_count``
field that media drivers
can use to track the number of users of every entity for power management
needs.
The &media_entity.@use_count field is owned by media drivers and must not be
The :c:type:`media_entity<media_entity>`.\ ``use_count`` field is owned by
media drivers and must not be
touched by entity drivers. Access to the field must be protected by the
&media_device.@graph_mutex lock.
:c:type:`media_device`.\ ``graph_mutex`` lock.
Links setup
^^^^^^^^^^^
Link properties can be modified at runtime by calling
media_entity_setup_link()
:cpp:func:`media_entity_setup_link()`.
Pipelines and media streams
^^^^^^^^^^^^^^^^^^^^^^^^^^^
When starting streaming, drivers must notify all entities in the pipeline to
prevent link states from being modified during streaming by calling
media_entity_pipeline_start().
:cpp:func:`media_entity_pipeline_start()`.
The function will mark all entities connected to the given entity through
enabled links, either directly or indirectly, as streaming.
The &media_pipeline instance pointed to by the pipe argument will be stored
in every entity in the pipeline. Drivers should embed the &media_pipeline
structure in higher-level pipeline structures and can then access the
pipeline through the &media_entity pipe field.
The :c:type:`struct media_pipeline <media_pipeline>` instance pointed to by
the pipe argument will be stored in every entity in the pipeline.
Drivers should embed the :c:type:`struct media_pipeline <media_pipeline>`
in higher-level pipeline structures and can then access the
pipeline through the :c:type:`struct media_entity <media_entity>`
pipe field.
Calls to media_entity_pipeline_start() can be nested. The pipeline pointer
must be identical for all nested calls to the function.
Calls to :cpp:func:`media_entity_pipeline_start()` can be nested.
The pipeline pointer must be identical for all nested calls to the function.
media_entity_pipeline_start() may return an error. In that case, it will
clean up any of the changes it did by itself.
:cpp:func:`media_entity_pipeline_start()` may return an error. In that case,
it will clean up any of the changes it did by itself.
When stopping the stream, drivers must notify the entities with
media_entity_pipeline_stop().
:cpp:func:`media_entity_pipeline_stop()`.
If multiple calls to media_entity_pipeline_start() have been made the same
number of media_entity_pipeline_stop() calls are required to stop streaming.
The &media_entity pipe field is reset to NULL on the last nested stop call.
If multiple calls to :cpp:func:`media_entity_pipeline_start()` have been
made the same number of :cpp:func:`media_entity_pipeline_stop()` calls
are required to stop streaming.
The :c:type:`media_entity`.\ ``pipe`` field is reset to ``NULL`` on the last
nested stop call.
Link configuration will fail with -%EBUSY by default if either end of the
Link configuration will fail with ``-EBUSY`` by default if either end of the
link is a streaming entity. Links that can be modified while streaming must
be marked with the %MEDIA_LNK_FL_DYNAMIC flag.
be marked with the ``MEDIA_LNK_FL_DYNAMIC`` flag.
If other operations need to be disallowed on streaming entities (such as
changing entities configuration parameters) drivers can explicitly check the
@ -227,13 +244,13 @@ operation must be done with the media_device graph_mutex held.
Link validation
^^^^^^^^^^^^^^^
Link validation is performed by media_entity_pipeline_start() for any
entity which has sink pads in the pipeline. The
&media_entity.@link_validate() callback is used for that purpose. In
@link_validate() callback, entity driver should check that the properties of
the source pad of the connected entity and its own sink pad match. It is up
to the type of the entity (and in the end, the properties of the hardware)
what matching actually means.
Link validation is performed by :cpp:func:`media_entity_pipeline_start()`
for any entity which has sink pads in the pipeline. The
:c:type:`media_entity`.\ ``link_validate()`` callback is used for that
purpose. In ``link_validate()`` callback, entity driver should check
that the properties of the source pad of the connected entity and its own
sink pad match. It is up to the type of the entity (and in the end, the
properties of the hardware) what matching actually means.
Subsystems should facilitate link validation by providing subsystem specific
helper functions to provide easy access for commonly needed information, and
@ -245,3 +262,10 @@ in the end provide a way to use driver-specific callbacks.
.. kernel-doc:: include/media/media-entity.h
.. kernel-doc:: include/media/media-device.h
:export: drivers/media/media-device.c
.. kernel-doc:: include/media/media-entity.h
:export: drivers/media/media-entity.c

View File

@ -242,13 +242,11 @@ void media_device_cleanup(struct media_device *mdev);
* without breaking binary compatibility. The version major must be
* incremented when binary compatibility is broken.
*
* Notes:
* .. note::
*
* 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.
* #) 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.
*
* Unregistering a media device that hasn't been registered is *NOT* safe.
* #) Unregistering a media device that hasn't been registered is **NOT** safe.
*
* Return: returns zero on success or a negative error code.
*/
@ -296,14 +294,16 @@ void media_device_unregister(struct media_device *mdev);
* This can be used to report the default audio and video devices or the
* default camera sensor.
*
* NOTE: Drivers should set the entity function before calling this function.
* .. note::
*
* Drivers should set the entity function before calling this function.
* Please notice that the values %MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN and
* %MEDIA_ENT_F_UNKNOWN should not be used by the drivers.
*/
int __must_check media_device_register_entity(struct media_device *mdev,
struct media_entity *entity);
/*
/**
* media_device_unregister_entity() - unregisters a media entity.
*
* @entity: pointer to struct &media_entity to be unregistered
@ -317,7 +317,9 @@ int __must_check media_device_register_entity(struct media_device *mdev,
* When a media device is unregistered, all its entities are unregistered
* automatically. No manual entities unregistration is then required.
*
* Note: the media_entity instance itself must be freed explicitly by
* .. note::
*
* The media_entity instance itself must be freed explicitly by
* the driver if required.
*/
void media_device_unregister_entity(struct media_entity *entity);

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@ -104,7 +104,7 @@ struct media_entity_graph {
int top;
};
/*
/**
* struct media_pipeline - Media pipeline related information
*
* @streaming_count: Streaming start count - streaming stop count
@ -180,7 +180,7 @@ struct media_pad {
* view. The media_entity_pipeline_start() function
* validates all links by calling this operation. Optional.
*
* Note: Those these callbacks are called with struct media_device.@graph_mutex
* .. note:: Those these callbacks are called with struct media_device.@graph_mutex
* mutex held.
*/
struct media_entity_operations {
@ -602,16 +602,17 @@ static inline void media_entity_cleanup(struct media_entity *entity) {};
* @flags: Link flags, as defined in include/uapi/linux/media.h.
*
* Valid values for flags:
* A %MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can be
* used to transfer media data. When two or more links target a sink pad,
*
* - A %MEDIA_LNK_FL_ENABLED flag indicates that the link is enabled and can
* be used to transfer media data. When two or more links target a sink pad,
* only one of them can be enabled at a time.
*
* A %MEDIA_LNK_FL_IMMUTABLE flag indicates that the link enabled state can't
* - A %MEDIA_LNK_FL_IMMUTABLE flag indicates that the link enabled state can't
* be modified at runtime. If %MEDIA_LNK_FL_IMMUTABLE is set, then
* %MEDIA_LNK_FL_ENABLED must also be set since an immutable link is
* always enabled.
*
* NOTE:
* .. note::
*
* Before calling this function, media_entity_pads_init() and
* media_device_register_entity() should be called previously for both ends.
@ -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
@ -677,7 +679,9 @@ 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
* .. note::
*
* This is called automatically when an entity is unregistered via
* media_device_register_entity().
*/
void media_entity_remove_links(struct media_entity *entity);
@ -728,7 +732,9 @@ 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
* .. 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.
*/
@ -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);
@ -909,7 +915,8 @@ struct media_link *
*
*
* Valid values for flags:
* The %MEDIA_LNK_FL_ENABLED flag indicates that the interface is connected to
*
* - 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.
@ -918,7 +925,7 @@ struct media_link *
* the V4L2 interfaces won't be enabled, as such device is not able to
* also stream analog TV or radio.
*
* Note:
* .. note::
*
* Before calling this function, media_devnode_create() should be called for
* the interface and media_device_register_entity() should be called for the
@ -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
* - 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);