ipa: ipu3: Document the IPAIPU3 class

Clarify the roles and interactions between the pipeline handler events
and the algorithm calls by documenting all the remaining functions of
the class.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Umang Jain <umang.jain@ideasonboard.com>

1 files changed, 76 insertions, 11 deletions

diff --git a/src/ipa/ipu3/ipu3.cpp b/src/ipa/ipu3/ipu3.cpp
index 1f501821..177b67b0 100644
--- a/src/ipa/ipu3/ipu3.cpp
+++ b/src/ipa/ipu3/ipu3.cpp
@@ -305,9 +305,9 @@ private:
 	struct IPAContext context_;
 };
 
-/*
- * Compute IPASessionConfiguration using the sensor information and the sensor
- * v4l2 controls.
+/**
+ * \brief Compute IPASessionConfiguration using the sensor information and the
+ * sensor V4L2 controls
  */
 void IPAIPU3::updateSessionConfiguration(const IPACameraSensorInfo &sensorInfo,
 					 const ControlInfoMap &sensorControls)
@@ -336,9 +336,9 @@ void IPAIPU3::updateSessionConfiguration(const IPACameraSensorInfo &sensorInfo,
 	context_.configuration.agc.maxAnalogueGain = camHelper_->gain(maxGain);
 }
 
-/*
- * Compute camera controls using the sensor information and the sensor
- * v4l2 controls.
+/**
+ * \brief Compute camera controls using the sensor information and the sensor
+ * V4L2 controls
  *
  * Some of the camera controls are computed by the pipeline handler, some others
  * by the IPA module which is in charge of handling, for example, the exposure
@@ -399,7 +399,7 @@ void IPAIPU3::updateControls(const IPACameraSensorInfo &sensorInfo,
 }
 
 /**
- * Initialize the IPA module and its controls.
+ * \brief Initialize the IPA module and its controls
  *
  * This function receives the camera sensor information from the pipeline
  * handler, computes the limits of the controls it handles and returns
@@ -430,8 +430,15 @@ int IPAIPU3::init(const IPASettings &settings,
 	return 0;
 }
 
+/**
+ * \brief Perform any processing required before the first frame
+ */
 int IPAIPU3::start()
 {
+	/*
+	 * Set the sensors V4L2 controls before the first frame to ensure that
+	 * we have an expected and known configuration from the start.
+	 */
 	setControls(0);
 
 	return 0;
@@ -512,7 +519,7 @@ void IPAIPU3::calculateBdsGrid(const Size &bdsOutputSize)
  * handler
  * \param[in] ipaControls The IPA controls to update
  *
- * Calculate the best grid for the statistics based on the Pipeline Handler BDS
+ * Calculate the best grid for the statistics based on the pipeline handler BDS
  * output, and parse the minimum and maximum exposure and analogue gain control
  * values.
  *
@@ -585,6 +592,10 @@ int IPAIPU3::configure(const IPAConfigInfo &configInfo,
 	return 0;
 }
 
+/**
+ * \brief Map the parameters and stats buffers allocated in the pipeline handler
+ * \param[in] buffers The buffers to map
+ */
 void IPAIPU3::mapBuffers(const std::vector<IPABuffer> &buffers)
 {
 	for (const IPABuffer &buffer : buffers) {
@@ -594,6 +605,10 @@ void IPAIPU3::mapBuffers(const std::vector<IPABuffer> &buffers)
 	}
 }
 
+/**
+ * \brief Unmap the parameters and stats buffers
+ * \param[in] ids The IDs of the buffers to unmap
+ */
 void IPAIPU3::unmapBuffers(const std::vector<unsigned int> &ids)
 {
 	for (unsigned int id : ids) {
@@ -605,6 +620,10 @@ void IPAIPU3::unmapBuffers(const std::vector<unsigned int> &ids)
 	}
 }
 
+/**
+ * \brief Process an event generated by the pipeline handler
+ * \param[in] event The event sent from pipeline handler
+ */
 void IPAIPU3::processEvent(const IPU3Event &event)
 {
 	switch (event.op) {
@@ -646,12 +665,28 @@ void IPAIPU3::processEvent(const IPU3Event &event)
 	}
 }
 
+/**
+ * \brief Process a control list for a request from the application
+ * \param[in] frame The number of the frame which will be processed next
+ * \param[in] controls The controls for the \a frame
+ *
+ * Parse the request to handle any IPA-managed controls that were set from the
+ * application such as manual sensor settings.
+ */
 void IPAIPU3::processControls([[maybe_unused]] unsigned int frame,
 			      [[maybe_unused]] const ControlList &controls)
 {
 	/* \todo Start processing for 'frame' based on 'controls'. */
 }
 
+/**
+ * \brief Fill the ImgU parameter buffer for the next frame
+ * \param[in] frame The number of the latest frame processed
+ * \param[out] params The parameter buffer to fill
+ *
+ * Algorithms are expected to fill the IPU3 parameter buffer for the next
+ * frame given their most recent processing of the ImgU statistics.
+ */
 void IPAIPU3::fillParams(unsigned int frame, ipu3_uapi_params *params)
 {
 	/*
@@ -674,6 +709,16 @@ void IPAIPU3::fillParams(unsigned int frame, ipu3_uapi_params *params)
 	queueFrameAction.emit(frame, op);
 }
 
+/**
+ * \brief Process the statistics generated by the ImgU
+ * \param[in] frame The number of the latest frame processed
+ * \param[in] frameTimestamp The current frame timestamp
+ * \param[in] stats The IPU3 statistics and ISP results
+ *
+ * Parse the most recently processed image statistics from the ImgU. The
+ * statistics are passed to each algorithm module to run their calculations and
+ * update their state accordingly.
+ */
 void IPAIPU3::parseStatistics(unsigned int frame,
 			      [[maybe_unused]] int64_t frameTimestamp,
 			      [[maybe_unused]] const ipu3_uapi_stats_3a *stats)
@@ -697,6 +742,13 @@ void IPAIPU3::parseStatistics(unsigned int frame,
 	queueFrameAction.emit(frame, op);
 }
 
+/**
+ * \brief Handle sensor controls for a given \a frame number
+ * \param[in] frame The frame on which the sensor controls should be set
+ *
+ * Send the desired sensor control values to the pipeline handler to request
+ * that they are applied on the camera sensor.
+ */
 void IPAIPU3::setControls(unsigned int frame)
 {
 	IPU3Action op;
@@ -715,10 +767,15 @@ void IPAIPU3::setControls(unsigned int frame)
 
 } /* namespace ipa::ipu3 */
 
-/*
- * External IPA module interface
+/**
+ * \brief External IPA module interface
+ *
+ * The IPAModuleInfo is required to match an IPA module construction against the
+ * intented pipeline handler with the module. The API and pipeline handler
+ * versions must match the corresponding IPA interface and pipeline handler.
+ *
+ * \sa struct IPAModuleInfo
  */
-
 extern "C" {
 const struct IPAModuleInfo ipaModuleInfo = {
 	IPA_MODULE_API_VERSION,
@@ -727,6 +784,14 @@ const struct IPAModuleInfo ipaModuleInfo = {
 	"ipu3",
 };
 
+/**
+ * \brief Create an instance of the IPA interface
+ *
+ * This function is the entry point of the IPA module. It is called by the IPA
+ * manager to create an instance of the IPA interface for each camera. When
+ * matched against with a pipeline handler, the IPAManager will construct an IPA
+ * instance for each associated Camera.
+ */
 IPAInterface *ipaCreate()
 {
 	return new ipa::ipu3::IPAIPU3();