[libcamera-devel,v3,22/38] libcamera: IPAInterface: remove ipa_context and functions from documentation

9930 diff mbox series

diff --git a/src/libcamera/ipa_interface.cpp b/src/libcamera/ipa_interface.cpp
index 23fc56d7..d989c75d 100644
--- a/src/libcamera/ipa_interface.cpp
+++ b/src/libcamera/ipa_interface.cpp
@@ -15,371 +15,52 @@ 
  * an Image Processing Algorithm (IPA) module. An IPA module is developed for a
  * specific pipeline handler and each pipeline handler may be compatible with
  * multiple IPA implementations, both open and closed source. To support this,
- * libcamera communicates with IPA modules through a standard plain C interface.
+ * libcamera communicates with IPA modules through a customizable C++ interface.
  *
  * IPA modules shall expose a public function named ipaCreate() with the
  * following prototype.
  *
  * \code{.c}
- * struct ipa_context *ipaCreate();
+ * IPAInterface *ipaCreate();
  * \endcode
  *
- * The ipaCreate() function creates an instance of an IPA context, which models
+ * The ipaCreate() function creates an instance of an IPA interface, which models
  * a context of execution for the IPA. IPA modules shall support creating one
  * context per camera, as required by their associated pipeline handler.
  *
- * The IPA module context operations are defined in the struct ipa_context_ops.
- * They model a low-level interface to configure the IPA, notify it of events,
- * and receive IPA actions through callbacks. An IPA module stores a pointer to
- * the operations corresponding to its context in the ipa_context::ops field.
- * That pointer is immutable for the lifetime of the context, and may differ
- * between different contexts created by the same IPA module.
+ * The IPA module interface operations are defined in the mojom file
+ * corresponding to the pipeline handler, in
+ * include/libcamera/ipa/{pipeline_name}.mojom. These interface operations and
+ * their parameters are completely customizable, and are meant to be written
+ * by the pipeline author.
  *
  * The IPA interface defines base data types and functions to exchange data. On
  * top of this, each pipeline handler is responsible for defining the set of
  * events and actions used to communicate with their IPA. These are collectively
  * referred to as IPA operations and define the pipeline handler-specific IPA
  * protocol. Each operation defines the data that it carries, and how that data
- * is encoded in the ipa_context_ops functions arguments.
+ * is encoded in the mojom file.
  *
  * \todo Add reference to how pipelines shall document their protocol.
  *
  * IPAs can be isolated in a separate process. This implies that arguments to
- * the IPA interface functions may need to be transferred over IPC. All
- * arguments use Plain Old Data types and are documented either in the form of C
- * data types, or as a textual description of byte arrays for types that can't
- * be expressed using C data types (such as arrays of mixed data types). IPA
- * modules can thus use the C API without calling into libcamera to access the
- * data passed to the IPA context operations.
+ * the IPA interface functions may need to be transferred over IPC. An IPA
+ * proxy is auto-generated based on the mojom file, which abstracts away the
+ * de/serialization from the pipeline handler and the IPA implementation. Thus
+ * any C++ struct that is defined in the mojom file, or the C++ libcamera
+ * objects that are mentioned in core.mojom, can be used directly.
  *
  * Due to IPC, synchronous communication between pipeline handlers and IPAs can
- * be costly. For that reason, the interface operates asynchronously. This
- * implies that methods don't return a status, and that all methods may copy
- * their arguments.
+ * be costly. For that reason, functions that cannot afford the high cost
+ * should be marked as [async] in the mojom file, and they will operate
+ * asynchronously. This implies that these methods don't return a status, and
+ * that all methods may copy their arguments. Synchronous functions are still
+ * allowed, but should be used with caution.
  *
- * The IPAInterface class is a C++ representation of the ipa_context_ops, using
- * C++ data classes provided by libcamera. This is the API exposed to pipeline
- * handlers to communicate with IPA modules. IPA modules may use the
- * IPAInterface API internally if they want to benefit from the data and helper
- * classes offered by libcamera.
- *
- * When an IPA module is loaded directly into the libcamera process and uses
- * the IPAInterface API internally, short-circuiting the path to the
- * ipa_context_ops and back to IPAInterface is desirable. To support this, IPA
- * modules may implement the ipa_context_ops::get_interface function to return a
- * pointer to their internal IPAInterface.
- */
-
-/**
- * \struct ipa_context
- * \brief IPA module context of execution
- *
- * This structure models a context of execution for an IPA module. It is
- * instantiated by the IPA module ipaCreate() function. IPA modules allocate
- * context instances in an implementation-defined way, contexts shall thus be
- * destroyed using the ipa_operation::destroy function only.
- *
- * The ipa_context structure provides a pointer to the IPA context operations.
- * It shall otherwise be treated as a constant black-box cookie and passed
- * unmodified to the functions defined in struct ipa_context_ops.
- *
- * IPA modules are expected to extend struct ipa_context by inheriting from it,
- * either through structure embedding to model inheritance in plain C, or
- * through C++ class inheritance. A simple example of the latter is available
- * in the IPAContextWrapper class implementation.
- *
- * \var ipa_context::ops
- * \brief The IPA context operations
- */
-
-/**
- * \struct ipa_settings
- * \brief IPA initialization settings for the IPA context operations
- * \sa IPASettings
- *
- * \var ipa_settings::configuration_file
- * \brief The name of the IPA configuration file (may be null or point to an
- * empty string)
- */
-
-/**
- * \struct ipa_sensor_info
- * \brief Camera sensor information for the IPA context operations
- * \sa libcamera::CameraSensorInfo
- *
- * \var ipa_sensor_info::model
- * \brief The camera sensor model name
- * \todo Remove this field as soon as no IPA depends on it anymore
- *
- * \var ipa_sensor_info::bits_per_pixel
- * \brief The camera sensor image format bit depth
- * \sa libcamera::CameraSensorInfo::bitsPerPixel
- *
- * \var ipa_sensor_info::active_area.width
- * \brief The camera sensor pixel array active area width
- * \sa libcamera::CameraSensorInfo::activeAreaSize
- *
- * \var ipa_sensor_info::active_area.height
- * \brief The camera sensor pixel array active area height
- * \sa libcamera::CameraSensorInfo::activeAreaSize
- *
- * \var ipa_sensor_info::active_area
- * \brief The camera sensor pixel array active size
- * \sa libcamera::CameraSensorInfo::activeAreaSize
- *
- * \var ipa_sensor_info::analog_crop.left
- * \brief The left coordinate of the analog crop rectangle, relative to the
- * pixel array active area
- * \sa libcamera::CameraSensorInfo::analogCrop
- *
- * \var ipa_sensor_info::analog_crop.top
- * \brief The top coordinate of the analog crop rectangle, relative to the pixel
- * array active area
- * \sa libcamera::CameraSensorInfo::analogCrop
- *
- * \var ipa_sensor_info::analog_crop.width
- * \brief The horizontal size of the analog crop rectangle
- * \sa libcamera::CameraSensorInfo::analogCrop
- *
- * \var ipa_sensor_info::analog_crop.height
- * \brief The vertical size of the analog crop rectangle
- * \sa libcamera::CameraSensorInfo::analogCrop
- *
- * \var ipa_sensor_info::analog_crop
- * \brief The analog crop rectangle
- * \sa libcamera::CameraSensorInfo::analogCrop
- *
- * \var ipa_sensor_info::output_size.width
- * \brief The horizontal size of the output image
- * \sa libcamera::CameraSensorInfo::outputSize
- *
- * \var ipa_sensor_info::output_size.height
- * \brief The vertical size of the output image
- * \sa libcamera::CameraSensorInfo::outputSize
- *
- * \var ipa_sensor_info::output_size
- * \brief The size of the output image
- * \sa libcamera::CameraSensorInfo::outputSize
- *
- * \var ipa_sensor_info::pixel_rate
- * \brief The number of pixel produced in a second
- * \sa libcamera::CameraSensorInfo::pixelRate
- *
- * \var ipa_sensor_info::line_length
- * \brief The full line length, including blanking, in pixel units
- * \sa libcamera::CameraSensorInfo::lineLength
- */
-
-/**
- * \struct ipa_stream
- * \brief Stream information for the IPA context operations
- *
- * \var ipa_stream::id
- * \brief Identifier for the stream, defined by the IPA protocol
- *
- * \var ipa_stream::pixel_format
- * \brief The stream pixel format, as defined by the PixelFormat class
- *
- * \var ipa_stream::width
- * \brief The stream width in pixels
- *
- * \var ipa_stream::height
- * \brief The stream height in pixels
- */
-
-/**
- * \struct ipa_control_info_map
- * \brief ControlInfoMap description for the IPA context operations
- *
- * \var ipa_control_info_map::id
- * \brief Identifier for the ControlInfoMap, defined by the IPA protocol
- *
- * \var ipa_control_info_map::data
- * \brief Pointer to a control packet for the ControlInfoMap
- * \sa ipa_controls.h
- *
- * \var ipa_control_info_map::size
- * \brief The size of the control packet in bytes
- */
-
-/**
- * \struct ipa_buffer_plane
- * \brief A plane for an ipa_buffer
- *
- * \var ipa_buffer_plane::dmabuf
- * \brief The dmabuf file descriptor for the plane (-1 for unused planes)
- *
- * \var ipa_buffer_plane::length
- * \brief The plane length in bytes (0 for unused planes)
- */
-
-/**
- * \struct ipa_buffer
- * \brief Buffer information for the IPA context operations
- *
- * \var ipa_buffer::id
- * \brief The buffer unique ID (see \ref libcamera::IPABuffer::id)
- *
- * \var ipa_buffer::num_planes
- * \brief The number of used planes in the ipa_buffer::planes array
- *
- * \var ipa_buffer::planes
- * \brief The buffer planes (up to 3)
- */
-
-/**
- * \struct ipa_control_list
- * \brief ControlList description for the IPA context operations
- *
- * \var ipa_control_list::data
- * \brief Pointer to a control packet for the ControlList
- * \sa ipa_controls.h
- *
- * \var ipa_control_list::size
- * \brief The size of the control packet in bytes
- */
-
-/**
- * \struct ipa_operation_data
- * \brief IPA operation data for the IPA context operations
- * \sa libcamera::IPAOperationData
- *
- * \var ipa_operation_data::operation
- * \brief IPA protocol operation
- *
- * \var ipa_operation_data::data
- * \brief Pointer to the operation data array
- *
- * \var ipa_operation_data::num_data
- * \brief Number of entries in the ipa_operation_data::data array
- *
- * \var ipa_operation_data::lists
- * \brief Pointer to an array of ipa_control_list
- *
- * \var ipa_operation_data::num_lists
- * \brief Number of entries in the ipa_control_list array
- */
-
-/**
- * \struct ipa_callback_ops
- * \brief IPA context operations as a set of function pointers
- */
-
-/**
- * \var ipa_callback_ops::queue_frame_action
- * \brief Queue an action associated with a frame to the pipeline handler
- * \param[in] cb_ctx The callback context registered with
- * ipa_context_ops::register_callbacks
- * \param[in] frame The frame number
- *
- * \sa libcamera::IPAInterface::queueFrameAction
- */
-
-/**
- * \struct ipa_context_ops
- * \brief IPA context operations as a set of function pointers
- *
- * To allow for isolation of IPA modules in separate processes, the functions
- * defined in the ipa_context_ops structure return only data related to the
- * libcamera side of the operations. In particular, error related to the
- * libcamera side of the IPC may be returned. Data returned by the IPA,
- * including status information, shall be provided through callbacks from the
- * IPA to libcamera.
- */
-
-/**
- * \var ipa_context_ops::destroy
- * \brief Destroy the IPA context created by the module's ipaCreate() function
- * \param[in] ctx The IPA context
- */
-
-/**
- * \var ipa_context_ops::get_interface
- * \brief Retrieve the IPAInterface implemented by the ipa_context (optional)
- * \param[in] ctx The IPA context
- *
- * IPA modules may implement this function to expose their internal
- * IPAInterface, if any. When implemented, libcamera may at its sole discretion
- * call it and then bypass the ipa_context_ops API by calling the IPAInterface
- * methods directly. IPA modules shall still implement and support the full
- * ipa_context_ops API.
- */
-
-/**
- * \var ipa_context_ops::init
- * \brief Initialise the IPA context
- * \param[in] ctx The IPA context
- * \param[in] settings The IPA initialization settings
- *
- * \sa libcamera::IPAInterface::init()
- */
-
-/**
- * \var ipa_context_ops::start
- * \brief Start the IPA context
- *
- * \sa libcamera::IPAInterface::start()
- */
-
-/**
- * \var ipa_context_ops::stop
- * \brief Stop the IPA context
- *
- * \sa libcamera::IPAInterface::stop()
- */
-
-/**
- * \var ipa_context_ops::register_callbacks
- * \brief Register callback operation from the IPA to the pipeline handler
- * \param[in] ctx The IPA context
- * \param[in] callback The IPA callback operations
- * \param[in] cb_ctx The callback context, passed to all callback operations
- */
-
-/**
- * \var ipa_context_ops::configure
- * \brief Configure the IPA stream and sensor settings
- * \param[in] ctx The IPA context
- * \param[in] sensor_info Camera sensor information
- * \param[in] streams Configuration of all active streams
- * \param[in] num_streams The number of entries in the \a streams array
- * \param[in] maps Controls provided by the pipeline entities
- * \param[in] num_maps The number of entries in the \a maps array
- *
- * \sa libcamera::IPAInterface::configure()
- */
-
-/**
- * \var ipa_context_ops::map_buffers
- * \brief Map buffers shared between the pipeline handler and the IPA
- * \param[in] ctx The IPA context
- * \param[in] buffers The buffers to map
- * \param[in] num_buffers The number of entries in the \a buffers array
- *
- * The dmabuf file descriptors provided in \a buffers are borrowed from the
- * caller and are only guaranteed to be valid during the map_buffers() call.
- * Should the callee need to store a copy of the file descriptors, it shall
- * duplicate them first with ::%dup().
- *
- * \sa libcamera::IPAInterface::mapBuffers()
- */
-
-/**
- * \var ipa_context_ops::unmap_buffers
- * \brief Unmap buffers shared by the pipeline to the IPA
- * \param[in] ctx The IPA context
- * \param[in] ids The IDs of the buffers to unmap
- * \param[in] num_buffers The number of entries in the \a ids array
- *
- * \sa libcamera::IPAInterface::unmapBuffers()
- */
-
-/**
- * \var ipa_context_ops::process_event
- * \brief Process an event from the pipeline handler
- * \param[in] ctx The IPA context
- *
- * \sa libcamera::IPAInterface::processEvent()
+ * The IPA interface, as defined in the respective mojom file, is the API
+ * exposed to pipeline handlers to communicate with IPA modules. IPA modules
+ * may use the IPAInterface API internally if they want to benefit from the
+ * data and helper classes offered by libcamera.
  */
 
 /**
@@ -387,9 +68,10 @@ 
  * \brief Entry point to the IPA modules
  *
  * This function is the entry point to the IPA modules. It is implemented by
- * every IPA module, and called by libcamera to create a new IPA context.
+ * every IPA module, and called by libcamera to create a new IPA interface
+ * instance.
  *
- * \return A newly created IPA context
+ * \return A newly created IPA interface instance
  */
 
 namespace libcamera {
@@ -499,157 +181,26 @@  namespace libcamera {
  * \class IPAInterface
  * \brief C++ Interface for IPA implementation
  *
- * This pure virtual class defines a C++ API corresponding to the ipa_context,
- * ipa_context_ops and ipa_callback_ops API. It is used by pipeline handlers to
+ * This pure virtual class defines a skeletal C++ API for IPA modules.
+ * Specializations of this class must be defined in a mojom file in
+ * include/libcamera/ipa/ (see include/libcamera/ipa/core.mojom for details
+ * on how to do so). The specialized class is used by pipeline handlers to
  * interact with IPA modules, and may be used internally in IPA modules if
  * desired to benefit from the data and helper classes provided by libcamera.
  *
- * Functions defined in the ipa_context_ops structure are mapped to IPAInterface
- * methods, while functions defined in the ipa_callback_ops are mapped to
- * IPAInterface signals. As with the C API, the IPA C++ interface uses
- * serializable data types only. It reuses structures defined by the C API, or
- * defines corresponding classes using C++ containers when required.
- *
  * Due to process isolation all arguments to the IPAInterface methods and
  * signals may need to be transferred over IPC. The class thus uses serializable
  * data types only. The IPA C++ interface defines custom data structures that
  * mirror core libcamera structures when the latter are not suitable, such as
  * IPAStream to carry StreamConfiguration data.
  *
- * As for the functions defined in struct ipa_context_ops, the methods defined
- * by this class shall not return data from the IPA.
+ * Custom data structures may also be defined in the mojom file, in which case
+ * the de/serialization will automatically be generated. If any other libcamera
+ * structures are to be used as parameters, then a de/serializer for them must
+ * be implemented in IPADataSerializer.
  *
  * The pipeline handler shall use the IPAManager to locate a compatible
  * IPAInterface. The interface may then be used to interact with the IPA module.
  */
 
-/**
- * \fn IPAInterface::init()
- * \brief Initialise the IPAInterface
- * \param[in] settings The IPA initialization settings
- *
- * This function initializes the IPA interface. It shall be called before any
- * other function of the IPAInterface. The \a settings carry initialization
- * parameters that are valid for the whole life time of the IPA interface.
- */
-
-/**
- * \fn IPAInterface::start()
- * \brief Start the IPA
- *
- * This method informs the IPA module that the camera is about to be started.
- * The IPA module shall prepare any resources it needs to operate.
- *
- * \return 0 on success or a negative error code otherwise
- */
-
-/**
- * \fn IPAInterface::stop()
- * \brief Stop the IPA
- *
- * This method informs the IPA module that the camera is stopped. The IPA module
- * shall release resources prepared in start().
- */
-
-/**
- * \fn IPAInterface::configure()
- * \brief Configure the IPA stream and sensor settings
- * \param[in] sensorInfo Camera sensor information
- * \param[in] streamConfig Configuration of all active streams
- * \param[in] entityControls Controls provided by the pipeline entities
- * \param[in] ipaConfig Pipeline-handler-specific configuration data
- * \param[out] result Pipeline-handler-specific configuration result
- *
- * This method shall be called when the camera is started to inform the IPA of
- * the camera's streams and the sensor settings. The meaning of the numerical
- * keys in the \a streamConfig and \a entityControls maps is defined by the IPA
- * protocol.
- *
- * The \a sensorInfo conveys information about the camera sensor settings that
- * the pipeline handler has selected for the configuration. The IPA may use
- * that information to tune its algorithms.
- *
- * The \a ipaConfig and \a result parameters carry custom data passed by the
- * pipeline handler to the IPA and back. The pipeline handler may set the \a
- * result parameter to null if the IPA protocol doesn't need to pass a result
- * back through the configure() function.
- */
-
-/**
- * \fn IPAInterface::mapBuffers()
- * \brief Map buffers shared between the pipeline handler and the IPA
- * \param[in] buffers List of buffers to map
- *
- * This method informs the IPA module of memory buffers set up by the pipeline
- * handler that the IPA needs to access. It provides dmabuf file handles for
- * each buffer, and associates the buffers with unique numerical IDs.
- *
- * IPAs shall map the dmabuf file handles to their address space and keep a
- * cache of the mappings, indexed by the buffer numerical IDs. The IDs are used
- * in all other IPA interface methods to refer to buffers, including the
- * unmapBuffers() method.
- *
- * All buffers that the pipeline handler wishes to share with an IPA shall be
- * mapped with this method. Buffers may be mapped all at once with a single
- * call, or mapped and unmapped dynamically at runtime, depending on the IPA
- * protocol. Regardless of the protocol, all buffers mapped at a given time
- * shall have unique numerical IDs.
- *
- * The numerical IDs have no meaning defined by the IPA interface, and IPA
- * protocols shall not give them any specific meaning either. They should be
- * treated as opaque handles by IPAs, with the only exception that ID zero is
- * invalid.
- *
- * \sa unmapBuffers()
- *
- * \todo Provide a generic implementation of mapBuffers and unmapBuffers for
- * IPAs
- */
-
-/**
- * \fn IPAInterface::unmapBuffers()
- * \brief Unmap buffers shared by the pipeline to the IPA
- * \param[in] ids List of buffer IDs to unmap
- *
- * This method removes mappings set up with mapBuffers(). Buffers may be
- * unmapped all at once with a single call, or selectively at runtime, depending
- * on the IPA protocol. Numerical IDs of unmapped buffers may be reused when
- * mapping new buffers.
- *
- * \sa mapBuffers()
- */
-
-/**
- * \fn IPAInterface::processEvent()
- * \brief Process an event from the pipeline handler
- * \param[in] data IPA operation data
- *
- * This operation is used by pipeline handlers to inform the IPA module of
- * events that occurred during the on-going capture operation.
- *
- * The event notified by the pipeline handler with this method is handled by the
- * IPA, which interprets the operation parameters according to the separately
- * documented IPA protocol.
- */
-
-/**
- * \var IPAInterface::queueFrameAction
- * \brief Queue an action associated with a frame to the pipeline handler
- * \param[in] frame The frame number for the action
- * \param[in] data IPA operation data
- *
- * This signal is emitted when the IPA wishes to queue a FrameAction on the
- * pipeline. The pipeline is still responsible for the scheduling of the action
- * on its timeline.
- *
- * This signal is emitted by the IPA to queue an action to be executed by the
- * pipeline handler on a frame. The type of action is identified by the
- * \a data.operation field, as defined by the IPA protocol, and the rest of the
- * \a data is interpreted accordingly. The pipeline handler shall queue the
- * action and execute it as appropriate.
- *
- * The signal is only emitted when the IPA is running, that is after start() and
- * before stop() have been called.
- */
-
 } /* namespace libcamera */