ipa: ipu3: Replace event-based ops with dedicated functions

The IPAIPU3 interface currently uses event-type based structures in
order to communicate with the pipeline-handler (and vice-versa).
Replace the event based structures with dedicated functions associated
to each operation.

The translated naming scheme of actions to signals are:
  ActionSetSensorControls => setSensorControls
  ActionParamFilled       => paramsBufferReady
  ActionMetadataReady     => metadataReady

The translated naming scheme of events to dedicated functions are:
  EventProcessControls    => queueRequest()
  EventStatReady          => processStatsBuffer()
  EventFillParams         => fillParamsBuffer()

The dedicated functions are called from pipeline-handler to the IPA
using IPC. These functions run asynchronously and when completed,
the IPA emits the respective signals as stated above in the translated
naming scheme.

The EventProcessControls is translated to queueRequest() to bring
symmetry to the IPU3 interface with other IPA interfaces.

Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>

4 files changed, 131 insertions, 184 deletions

diff --git a/include/libcamera/ipa/ipu3.mojom b/include/libcamera/ipa/ipu3.mojom
index 18cdc744..d1b1c6b8 100644
--- a/include/libcamera/ipa/ipu3.mojom
+++ b/include/libcamera/ipa/ipu3.mojom
@@ -8,32 +8,6 @@ module ipa.ipu3;
 
 import "include/libcamera/ipa/core.mojom";
 
-enum IPU3Operations {
-	ActionSetSensorControls = 1,
-	ActionParamFilled = 2,
-	ActionMetadataReady = 3,
-	EventProcessControls = 4,
-	EventStatReady = 5,
-	EventFillParams = 6,
-};
-
-struct IPU3Event {
-	IPU3Operations op;
-	uint32 frame;
-	int64 frameTimestamp;
-	uint32 bufferId;
-	libcamera.ControlList controls;
-	libcamera.ControlList sensorControls;
-	libcamera.ControlList lensControls;
-};
-
-struct IPU3Action {
-	IPU3Operations op;
-	libcamera.ControlList controls;
-	libcamera.ControlList sensorControls;
-	libcamera.ControlList lensControls;
-};
-
 struct IPAConfigInfo {
 	libcamera.IPACameraSensorInfo sensorInfo;
 	libcamera.ControlInfoMap sensorControls;
@@ -56,9 +30,15 @@ interface IPAIPU3Interface {
 	mapBuffers(array<libcamera.IPABuffer> buffers);
 	unmapBuffers(array<uint32> ids);
 
-	[async] processEvent(IPU3Event ev);
+	[async] queueRequest(uint32 frame, libcamera.ControlList controls);
+	[async] fillParamsBuffer(uint32 frame, uint32 bufferId);
+	[async] processStatsBuffer(uint32 frame, int64 frameTimestamp,
+				   uint32 bufferId, libcamera.ControlList sensorControls);
 };
 
 interface IPAIPU3EventInterface {
-	queueFrameAction(uint32 frame, IPU3Action action);
+	setSensorControls(uint32 frame, libcamera.ControlList sensorControls,
+			  libcamera.ControlList lensControls);
+	paramsBufferReady(uint32 frame);
+	metadataReady(uint32 frame, libcamera.ControlList metadata);
 };
diff --git a/src/ipa/ipu3/ipu3-ipa-design-guide.rst b/src/ipa/ipu3/ipu3-ipa-design-guide.rst
index 89c71108..e724fdda 100644
--- a/src/ipa/ipu3/ipu3-ipa-design-guide.rst
+++ b/src/ipa/ipu3/ipu3-ipa-design-guide.rst
@@ -25,7 +25,8 @@ from applications, and managing events from the pipeline handler.
       └─┬───┬───┬──────┬────┬────┬────┬─┴────▼─┬──┘    1: init()
         │   │   │      │ ▲  │ ▲  │ ▲  │ ▲      │       2: configure()
         │1  │2  │3     │4│  │4│  │4│  │4│      │5      3: mapBuffers(), start()
-        ▼   ▼   ▼      ▼ │  ▼ │  ▼ │  ▼ │      ▼       4: processEvent()
+        │   │   │      │ │  │ │  │ │  │ │      │       4: (▼) queueRequest(), fillParamsBuffer(), processStatsBuffer()
+        ▼   ▼   ▼      ▼ │  ▼ │  ▼ │  ▼ │      ▼          (▲) setSensorControls, paramsBufferReady, metadataReady Signals
       ┌──────────────────┴────┴────┴────┴─────────┐    5: stop(), unmapBuffers()
       │ IPU3 IPA                                  │
       │                 ┌───────────────────────┐ │
@@ -100,8 +101,9 @@ There are three main interactions with the algorithms for the IPU3 IPA
 to operate when running:
 
 -  configure()
--  processEvent(``EventFillParams``)
--  processEvent(``EventStatReady``)
+-  queueRequest()
+-  fillParamsBuffer()
+-  processStatsBuffer()
 
 The configuration phase allows the pipeline-handler to inform the IPA of
 the current stream configurations, which is then passed into each
@@ -114,8 +116,8 @@ Pre-frame preparation
 When configured, the IPA is notified by the pipeline handler of the
 Camera ``start()`` event, after which incoming requests will be queued
 for processing, requiring a parameter buffer (``ipu3_uapi_params``) to
-be populated for the ImgU. This is given to the IPA through the
-``EventFillParams`` event, and then passed directly to each algorithm
+be populated for the ImgU. This is given to the IPA through
+``fillParamsBuffer()``, and then passed directly to each algorithm
 through the ``prepare()`` call allowing the ISP configuration to be
 updated for the needs of each component that the algorithm is
 responsible for.
@@ -125,7 +127,7 @@ structure that it modifies, and it should take care to ensure that any
 structure set by a use flag is fully initialised to suitable values.
 
 The parameter buffer is returned to the pipeline handler through the
-``ActionParamFilled`` event, and from there queued to the ImgU along
+``paramsBufferReady`` signal, and from there queued to the ImgU along
 with a raw frame captured with the CIO2.
 
 Post-frame completion
@@ -133,8 +135,8 @@ Post-frame completion
 
 When the capture of an image is completed, and successfully processed
 through the ImgU, the generated statistics buffer
-(``ipu3_uapi_stats_3a``) is given to the IPA through the
-``EventStatReady`` event. This provides the IPA with an opportunity to
+(``ipu3_uapi_stats_3a``) is given to the IPA through
+``processStatsBuffer()``. This provides the IPA with an opportunity to
 examine the results of the ISP and run the calculations required by each
 algorithm on the new data. The algorithms may require context from the
 operations of other algorithms, for example, the AWB might choose to use
@@ -145,11 +147,14 @@ before they are needed.
 The ordering of the algorithm processing is determined by their
 placement in the ``IPU3::algorithms_`` ordered list.
 
+Finally, the IPA metadata for the completed frame is returned back via
+the ``metadataReady`` signal.
+
 Sensor Controls
 ~~~~~~~~~~~~~~~
 
 The AutoExposure and AutoGain (AGC) algorithm differs slightly from the
 others as it requires operating directly on the sensor, as opposed to
-through the ImgU ISP. To support this, there is a dedicated action
-`ActionSetSensorControls` to allow the IPA to request controls to be set
-on the camera sensor through the pipeline handler.
+through the ImgU ISP. To support this, there is a ``setSensorControls``
+signal to allow the IPA to request controls to be set on the camera
+sensor through the pipeline handler.
diff --git a/src/ipa/ipu3/ipu3.cpp b/src/ipa/ipu3/ipu3.cpp
index 50b52d8b..14f3f91e 100644
--- a/src/ipa/ipu3/ipu3.cpp
+++ b/src/ipa/ipu3/ipu3.cpp
@@ -65,8 +65,9 @@ namespace ipa::ipu3 {
  * The IPU3 Pipeline defines an IPU3-specific interface for communication
  * between the PipelineHandler and the IPA module.
  *
- * We extend the IPAIPU3Interface to implement our algorithms and handle events
- * from the IPU3 PipelineHandler to satisfy requests from the application.
+ * We extend the IPAIPU3Interface to implement our algorithms and handle
+ * calls from the IPU3 PipelineHandler to satisfy requests from the
+ * application.
  *
  * At initialisation time, a CameraSensorHelper is instantiated to support
  * camera-specific calculations, while the default controls are computed, and
@@ -81,14 +82,14 @@ namespace ipa::ipu3 {
  * parameter buffer, and adapting the settings of the sensor attached to the
  * IPU3 CIO2 through sensor-specific V4L2 controls.
  *
- * When the event \a EventFillParams occurs we populate the ImgU parameter
- * buffer with settings to configure the device in preparation for handling the
- * frame queued in the Request.
+ * In fillParamsBuffer(), we populate the ImgU parameter buffer with
+ * settings to configure the device in preparation for handling the frame
+ * queued in the Request.
  *
  * When the frame has completed processing, the ImgU will generate a statistics
- * buffer which is given to the IPA as part of the \a EventStatReady event. At
- * this event we run the algorithms to parse the statistics and cache any
- * results for the next \a EventFillParams event.
+ * buffer which is given to the IPA with processStatsBuffer(). In this we run the
+ * algorithms to parse the statistics and cache any results for the next
+ * fillParamsBuffer() call.
  *
  * The individual algorithms are split into modular components that are called
  * iteratively to allow them to process statistics from the ImgU in a defined
@@ -143,14 +144,18 @@ public:
 
 	void mapBuffers(const std::vector<IPABuffer> &buffers) override;
 	void unmapBuffers(const std::vector<unsigned int> &ids) override;
-	void processEvent(const IPU3Event &event) override;
 
+	void queueRequest(const uint32_t frame, const ControlList &controls) override;
+	void fillParamsBuffer(const uint32_t frame, const uint32_t bufferId) override;
+	void processStatsBuffer(const uint32_t frame, const int64_t frameTimestamp,
+				const uint32_t bufferId,
+				const ControlList &sensorControls) override;
 private:
 	void updateControls(const IPACameraSensorInfo &sensorInfo,
 			    const ControlInfoMap &sensorControls,
 			    ControlInfoMap *ipaControls);
 	void updateSessionConfiguration(const ControlInfoMap &sensorControls);
-	void processControls(unsigned int frame, const ControlList &controls);
+
 	void fillParams(unsigned int frame, ipu3_uapi_params *params);
 	void parseStatistics(unsigned int frame,
 			     int64_t frameTimestamp,
@@ -505,73 +510,62 @@ 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
- *
- * The expected event handling over the lifetime of a Request has
- * the following sequence:
- *
- *   - EventProcessControls : Handle controls from a new Request
- *   - EventFillParams : Prepare the ISP to process the Request
- *   - EventStatReady : Process statistics after ISP completion
+ * \brief Fill and return a buffer with ISP processing parameters for a frame
+ * \param[in] frame The frame number
+ * \param[in] bufferId ID of the parameter buffer to fill
  */
-void IPAIPU3::processEvent(const IPU3Event &event)
+void IPAIPU3::fillParamsBuffer(const uint32_t frame, const uint32_t bufferId)
 {
-	switch (event.op) {
-	case EventProcessControls: {
-		processControls(event.frame, event.controls);
-		break;
+	auto it = buffers_.find(bufferId);
+	if (it == buffers_.end()) {
+		LOG(IPAIPU3, Error) << "Could not find param buffer!";
+		return;
 	}
-	case EventFillParams: {
-		auto it = buffers_.find(event.bufferId);
-		if (it == buffers_.end()) {
-			LOG(IPAIPU3, Error) << "Could not find param buffer!";
-			return;
-		}
 
-		Span<uint8_t> mem = it->second.planes()[0];
-		ipu3_uapi_params *params =
-			reinterpret_cast<ipu3_uapi_params *>(mem.data());
+	Span<uint8_t> mem = it->second.planes()[0];
+	ipu3_uapi_params *params =
+		reinterpret_cast<ipu3_uapi_params *>(mem.data());
 
-		fillParams(event.frame, params);
-		break;
-	}
-	case EventStatReady: {
-		auto it = buffers_.find(event.bufferId);
-		if (it == buffers_.end()) {
-			LOG(IPAIPU3, Error) << "Could not find stats buffer!";
-			return;
-		}
+	fillParams(frame, params);
+}
 
-		Span<uint8_t> mem = it->second.planes()[0];
-		const ipu3_uapi_stats_3a *stats =
-			reinterpret_cast<ipu3_uapi_stats_3a *>(mem.data());
+/**
+ * \brief Process statistics after ISP completion
+ * \param[in] frame The frame number
+ * \param[in] frameTimestamp Timestamp of the frame
+ * \param[in] bufferId ID of the statistics buffer
+ * \param[in] sensorControls Sensor controls
+ */
+void IPAIPU3::processStatsBuffer(const uint32_t frame,
+				 [[maybe_unused]] const int64_t frameTimestamp,
+				 const uint32_t bufferId, const ControlList &sensorControls)
+{
+	auto it = buffers_.find(bufferId);
+	if (it == buffers_.end()) {
+		LOG(IPAIPU3, Error) << "Could not find stats buffer!";
+		return;
+	}
 
-		int32_t exposure = event.sensorControls.get(V4L2_CID_EXPOSURE).get<int32_t>();
-		int32_t gain = event.sensorControls.get(V4L2_CID_ANALOGUE_GAIN).get<int32_t>();
+	Span<uint8_t> mem = it->second.planes()[0];
+	const ipu3_uapi_stats_3a *stats =
+		reinterpret_cast<ipu3_uapi_stats_3a *>(mem.data());
 
-		context_.frameContext.sensor.exposure = exposure;
-		context_.frameContext.sensor.gain = camHelper_->gain(gain);
+	context_.frameContext.sensor.exposure = sensorControls.get(V4L2_CID_EXPOSURE).get<int32_t>();
+	context_.frameContext.sensor.gain = camHelper_->gain(sensorControls.get(V4L2_CID_ANALOGUE_GAIN).get<int32_t>());
 
-		parseStatistics(event.frame, event.frameTimestamp, stats);
-		break;
-	}
-	default:
-		LOG(IPAIPU3, Error) << "Unknown event " << event.op;
-		break;
-	}
+	parseStatistics(frame, frameTimestamp, stats);
 }
 
 /**
- * \brief Process a control list for a request from the application
+ * \brief Queue a request and process the control list 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)
+void IPAIPU3::queueRequest([[maybe_unused]] const uint32_t frame,
+			   [[maybe_unused]] const ControlList &controls)
 {
 	/* \todo Start processing for 'frame' based on 'controls'. */
 }
@@ -600,10 +594,7 @@ void IPAIPU3::fillParams(unsigned int frame, ipu3_uapi_params *params)
 	for (auto const &algo : algorithms_)
 		algo->prepare(context_, params);
 
-	IPU3Action op;
-	op.op = ActionParamFilled;
-
-	queueFrameAction.emit(frame, op);
+	paramsBufferReady.emit(frame);
 }
 
 /**
@@ -647,11 +638,7 @@ void IPAIPU3::parseStatistics(unsigned int frame,
 	 * likely want to avoid putting platform specific metadata in.
 	 */
 
-	IPU3Action op;
-	op.op = ActionMetadataReady;
-	op.controls = ctrls;
-
-	queueFrameAction.emit(frame, op);
+	metadataReady.emit(frame, ctrls);
 }
 
 /**
@@ -663,23 +650,18 @@ void IPAIPU3::parseStatistics(unsigned int frame,
  */
 void IPAIPU3::setControls(unsigned int frame)
 {
-	IPU3Action op;
-	op.op = ActionSetSensorControls;
-
 	int32_t exposure = context_.frameContext.agc.exposure;
 	int32_t gain = camHelper_->gainCode(context_.frameContext.agc.gain);
 
 	ControlList ctrls(sensorCtrls_);
 	ctrls.set(V4L2_CID_EXPOSURE, exposure);
 	ctrls.set(V4L2_CID_ANALOGUE_GAIN, gain);
-	op.sensorControls = ctrls;
 
 	ControlList lensCtrls(lensCtrls_);
 	lensCtrls.set(V4L2_CID_FOCUS_ABSOLUTE,
 		      static_cast<int32_t>(context_.frameContext.af.focus));
-	op.lensControls = lensCtrls;
 
-	queueFrameAction.emit(frame, op);
+	setSensorControls.emit(frame, ctrls, lensCtrls);
 }
 
 } /* namespace ipa::ipu3 */
diff --git a/src/libcamera/pipeline/ipu3/ipu3.cpp b/src/libcamera/pipeline/ipu3/ipu3.cpp
index 60e01917..9f113171 100644
--- a/src/libcamera/pipeline/ipu3/ipu3.cpp
+++ b/src/libcamera/pipeline/ipu3/ipu3.cpp
@@ -86,8 +86,10 @@ public:
 	ControlInfoMap ipaControls_;
 
 private:
-	void queueFrameAction(unsigned int id,
-			      const ipa::ipu3::IPU3Action &action);
+	void metadataReady(unsigned int id, const ControlList &metadata);
+	void paramsBufferReady(unsigned int id);
+	void setSensorControls(unsigned int id, const ControlList &sensorControls,
+			       const ControlList &lensControls);
 };
 
 class IPU3CameraConfiguration : public CameraConfiguration
@@ -871,11 +873,7 @@ void IPU3CameraData::queuePendingRequests()
 
 		info->rawBuffer = rawBuffer;
 
-		ipa::ipu3::IPU3Event ev;
-		ev.op = ipa::ipu3::EventProcessControls;
-		ev.frame = info->id;
-		ev.controls = request->controls();
-		ipa_->processEvent(ev);
+		ipa_->queueRequest(info->id, request->controls());
 
 		pendingRequests_.pop();
 		processingRequests_.push(request);
@@ -1218,7 +1216,9 @@ int IPU3CameraData::loadIPA()
 	if (!ipa_)
 		return -ENOENT;
 
-	ipa_->queueFrameAction.connect(this, &IPU3CameraData::queueFrameAction);
+	ipa_->setSensorControls.connect(this, &IPU3CameraData::setSensorControls);
+	ipa_->paramsBufferReady.connect(this, &IPU3CameraData::paramsBufferReady);
+	ipa_->metadataReady.connect(this, &IPU3CameraData::metadataReady);
 
 	/*
 	 * Pass the sensor info to the IPA to initialize controls.
@@ -1253,69 +1253,58 @@ int IPU3CameraData::loadIPA()
 	return 0;
 }
 
-void IPU3CameraData::queueFrameAction(unsigned int id,
-				      const ipa::ipu3::IPU3Action &action)
+void IPU3CameraData::setSensorControls([[maybe_unused]] unsigned int id,
+				       const ControlList &sensorControls,
+				       const ControlList &lensControls)
 {
-	switch (action.op) {
-	case ipa::ipu3::ActionSetSensorControls: {
-		const ControlList &sensorControls = action.sensorControls;
-		delayedCtrls_->push(sensorControls);
+	delayedCtrls_->push(sensorControls);
 
-		CameraLens *focusLens = cio2_.sensor()->focusLens();
-		if (!focusLens)
-			break;
-
-		const ControlList lensControls = action.lensControls;
-		if (!lensControls.contains(V4L2_CID_FOCUS_ABSOLUTE))
-			break;
+	CameraLens *focusLens = cio2_.sensor()->focusLens();
+	if (!focusLens)
+		return;
 
-		const ControlValue &focusValue =
-			lensControls.get(V4L2_CID_FOCUS_ABSOLUTE);
+	if (!lensControls.contains(V4L2_CID_FOCUS_ABSOLUTE))
+		return;
 
-		focusLens->setFocusPosition(focusValue.get<int32_t>());
+	const ControlValue &focusValue = lensControls.get(V4L2_CID_FOCUS_ABSOLUTE);
 
-		break;
-	}
-	case ipa::ipu3::ActionParamFilled: {
-		IPU3Frames::Info *info = frameInfos_.find(id);
-		if (!info)
-			break;
-
-		/* Queue all buffers from the request aimed for the ImgU. */
-		for (auto it : info->request->buffers()) {
-			const Stream *stream = it.first;
-			FrameBuffer *outbuffer = it.second;
+	focusLens->setFocusPosition(focusValue.get<int32_t>());
+}
 
-			if (stream == &outStream_)
-				imgu_->output_->queueBuffer(outbuffer);
-			else if (stream == &vfStream_)
-				imgu_->viewfinder_->queueBuffer(outbuffer);
-		}
+void IPU3CameraData::paramsBufferReady(unsigned int id)
+{
+	IPU3Frames::Info *info = frameInfos_.find(id);
+	if (!info)
+		return;
 
-		imgu_->param_->queueBuffer(info->paramBuffer);
-		imgu_->stat_->queueBuffer(info->statBuffer);
-		imgu_->input_->queueBuffer(info->rawBuffer);
+	/* Queue all buffers from the request aimed for the ImgU. */
+	for (auto it : info->request->buffers()) {
+		const Stream *stream = it.first;
+		FrameBuffer *outbuffer = it.second;
 
-		break;
+		if (stream == &outStream_)
+			imgu_->output_->queueBuffer(outbuffer);
+		else if (stream == &vfStream_)
+			imgu_->viewfinder_->queueBuffer(outbuffer);
 	}
-	case ipa::ipu3::ActionMetadataReady: {
-		IPU3Frames::Info *info = frameInfos_.find(id);
-		if (!info)
-			break;
 
-		Request *request = info->request;
-		request->metadata().merge(action.controls);
+	imgu_->param_->queueBuffer(info->paramBuffer);
+	imgu_->stat_->queueBuffer(info->statBuffer);
+	imgu_->input_->queueBuffer(info->rawBuffer);
+}
 
-		info->metadataProcessed = true;
-		if (frameInfos_.tryComplete(info))
-			pipe()->completeRequest(request);
+void IPU3CameraData::metadataReady(unsigned int id, const ControlList &metadata)
+{
+	IPU3Frames::Info *info = frameInfos_.find(id);
+	if (!info)
+		return;
 
-		break;
-	}
-	default:
-		LOG(IPU3, Error) << "Unknown action " << action.op;
-		break;
-	}
+	Request *request = info->request;
+	request->metadata().merge(metadata);
+
+	info->metadataProcessed = true;
+	if (frameInfos_.tryComplete(info))
+		pipe()->completeRequest(request);
 }
 
 /* -----------------------------------------------------------------------------
@@ -1390,11 +1379,7 @@ void IPU3CameraData::cio2BufferReady(FrameBuffer *buffer)
 	if (request->findBuffer(&rawStream_))
 		pipe()->completeBuffer(request, buffer);
 
-	ipa::ipu3::IPU3Event ev;
-	ev.op = ipa::ipu3::EventFillParams;
-	ev.frame = info->id;
-	ev.bufferId = info->paramBuffer->cookie();
-	ipa_->processEvent(ev);
+	ipa_->fillParamsBuffer(info->id, info->paramBuffer->cookie());
 }
 
 void IPU3CameraData::paramBufferReady(FrameBuffer *buffer)
@@ -1438,13 +1423,8 @@ void IPU3CameraData::statBufferReady(FrameBuffer *buffer)
 		return;
 	}
 
-	ipa::ipu3::IPU3Event ev;
-	ev.op = ipa::ipu3::EventStatReady;
-	ev.frame = info->id;
-	ev.bufferId = info->statBuffer->cookie();
-	ev.frameTimestamp = request->metadata().get(controls::SensorTimestamp);
-	ev.sensorControls = info->effectiveSensorControls;
-	ipa_->processEvent(ev);
+	ipa_->processStatsBuffer(info->id, request->metadata().get(controls::SensorTimestamp),
+				 info->statBuffer->cookie(), info->effectiveSensorControls);
 }
 
 /*