rkisp1: Honor the FrameDurationLimits control

Add support to rkisp1 for controlling the framerate via the
FrameDurationLimits control.

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

src/ipa/rkisp1/algorithms/agc.cpp

@@ -190,6 +190,7 @@ int Agc::configure(IPAContext &context, const IPACameraSensorInfo &configInfo)
 
 	/* Limit the frame duration to match current initialisation */
 	ControlInfo &frameDurationLimits = context.ctrlMap[&controls::FrameDurationLimits];
+	context.activeState.agc.minFrameDuration = std::chrono::microseconds(frameDurationLimits.min().get<int64_t>());
 	context.activeState.agc.maxFrameDuration = std::chrono::microseconds(frameDurationLimits.max().get<int64_t>());
 
 	/*
@@ -307,10 +308,21 @@ void Agc::queueRequest(IPAContext &context,
 
 	const auto &frameDurationLimits = controls.get(controls::FrameDurationLimits);
 	if (frameDurationLimits) {
-		utils::Duration maxFrameDuration =
+		/* Limit the control value to the limits in ControlInfo */
-			std::chrono::milliseconds((*frameDurationLimits).back());
+		ControlInfo &limits = context.ctrlMap[&controls::FrameDurationLimits];
-		agc.maxFrameDuration = maxFrameDuration;
+		int64_t minFrameDuration =
+			std::clamp((*frameDurationLimits).front(),
+				   limits.min().get<int64_t>(),
+				   limits.max().get<int64_t>());
+		int64_t maxFrameDuration =
+			std::clamp((*frameDurationLimits).back(),
+				   limits.min().get<int64_t>(),
+				   limits.max().get<int64_t>());
+
+		agc.minFrameDuration = std::chrono::microseconds(minFrameDuration);
+		agc.maxFrameDuration = std::chrono::microseconds(maxFrameDuration);
 	}
+	frameContext.agc.minFrameDuration = agc.minFrameDuration;
 	frameContext.agc.maxFrameDuration = agc.maxFrameDuration;
 }
 
@@ -387,6 +399,7 @@ void Agc::fillMetadata(IPAContext &context, IPAFrameContext &frameContext,
 				     * frameContext.sensor.exposure;
 	metadata.set(controls::AnalogueGain, frameContext.sensor.gain);
 	metadata.set(controls::ExposureTime, exposureTime.get<std::micro>());
+	metadata.set(controls::FrameDuration, frameContext.agc.frameDuration.get<std::micro>());
 	metadata.set(controls::ExposureTimeMode,
 		     frameContext.agc.autoExposureEnabled
 		     ? controls::ExposureTimeModeAuto
@@ -396,13 +409,6 @@ void Agc::fillMetadata(IPAContext &context, IPAFrameContext &frameContext,
 		     ? controls::AnalogueGainModeAuto
 		     : controls::AnalogueGainModeManual);
 
-	/* \todo Use VBlank value calculated from each frame exposure. */
-	uint32_t vTotal = context.configuration.sensor.size.height
-			+ context.configuration.sensor.defVBlank;
-	utils::Duration frameDuration = context.configuration.sensor.lineDuration
-				      * vTotal;
-	metadata.set(controls::FrameDuration, frameDuration.get<std::micro>());
-
 	metadata.set(controls::AeMeteringMode, frameContext.agc.meteringMode);
 	metadata.set(controls::AeExposureMode, frameContext.agc.exposureMode);
 	metadata.set(controls::AeConstraintMode, frameContext.agc.constraintMode);
@@ -444,6 +450,27 @@ double Agc::estimateLuminance(double gain) const
 	return ySum / expMeans_.size() / 255;
 }
 
+/**
+ * \brief Process frame duration and compute vblank
+ * \param[in] context The shared IPA context
+ * \param[in] frameContext The current frame context
+ * \param[in] frameDuration The target frame duration
+ *
+ * Compute and populate vblank from the target frame duration.
+ */
+void Agc::processFrameDuration(IPAContext &context,
+			       IPAFrameContext &frameContext,
+			       utils::Duration frameDuration)
+{
+	IPACameraSensorInfo &sensorInfo = context.sensorInfo;
+	utils::Duration lineDuration = context.configuration.sensor.lineDuration;
+
+	frameContext.agc.vblank = (frameDuration / lineDuration) - sensorInfo.outputSize.height;
+
+	/* Update frame duration accounting for line length quantization. */
+	frameContext.agc.frameDuration = (sensorInfo.outputSize.height + frameContext.agc.vblank) * lineDuration;
+}
+
 /**
  * \brief Process RkISP1 statistics, and run AGC operations
  * \param[in] context The shared IPA context
@@ -460,6 +487,8 @@ void Agc::process(IPAContext &context, [[maybe_unused]] const uint32_t frame,
 		  ControlList &metadata)
 {
 	if (!stats) {
+		processFrameDuration(context, frameContext,
+				     frameContext.agc.minFrameDuration);
 		fillMetadata(context, frameContext, metadata);
 		return;
 	}
@@ -497,7 +526,9 @@ void Agc::process(IPAContext &context, [[maybe_unused]] const uint32_t frame,
 	double maxAnalogueGain;
 
 	if (frameContext.agc.autoExposureEnabled) {
-		minExposureTime = context.configuration.sensor.minExposureTime;
+		minExposureTime = std::clamp(frameContext.agc.minFrameDuration,
+					     context.configuration.sensor.minExposureTime,
+					     context.configuration.sensor.maxExposureTime);
 		maxExposureTime = std::clamp(frameContext.agc.maxFrameDuration,
 					     context.configuration.sensor.minExposureTime,
 					     context.configuration.sensor.maxExposureTime);
@@ -541,6 +572,13 @@ void Agc::process(IPAContext &context, [[maybe_unused]] const uint32_t frame,
 	activeState.agc.automatic.exposure = newExposureTime / lineDuration;
 	activeState.agc.automatic.gain = aGain;
 
+	/*
+	 * Expand the target frame duration so that we do not run faster than
+	 * the minimum frame duration when we have short exposures.
+	 */
+	processFrameDuration(context, frameContext,
+			     std::max(frameContext.agc.minFrameDuration, newExposureTime));
+
 	fillMetadata(context, frameContext, metadata);
 	expMeans_ = {};
 }

src/ipa/rkisp1/algorithms/agc.h

@@ -50,6 +50,9 @@ private:
 	void fillMetadata(IPAContext &context, IPAFrameContext &frameContext,
 			  ControlList &metadata);
 	double estimateLuminance(double gain) const override;
+	void processFrameDuration(IPAContext &context,
+				  IPAFrameContext &frameContext,
+				  utils::Duration frameDuration);
 
 	Span<const uint8_t> expMeans_;
 

src/ipa/rkisp1/ipa_context.cpp

@@ -180,6 +180,9 @@ namespace libcamera::ipa::rkisp1 {
  * \var IPAActiveState::agc.meteringMode
  * \brief Metering mode as set by the AeMeteringMode control
  *
+ * \var IPAActiveState::agc.minFrameDuration
+ * \brief Minimum frame duration as set by the FrameDurationLimits control
+ *
  * \var IPAActiveState::agc.maxFrameDuration
  * \brief Maximum frame duration as set by the FrameDurationLimits control
  */
@@ -282,7 +285,9 @@ namespace libcamera::ipa::rkisp1 {
  * \brief Automatic Gain Control parameters for this frame
  *
  * The exposure and gain are provided by the AGC algorithm, and are to be
- * applied to the sensor in order to take effect for this frame.
+ * applied to the sensor in order to take effect for this frame. Additionally
+ * the vertical blanking period is determined to maintain a consistent frame
+ * rate matched to the FrameDurationLimits as set by the user.
  *
  * \var IPAFrameContext::agc.exposure
  * \brief Exposure time expressed as a number of lines computed by the algorithm
@@ -292,6 +297,9 @@ namespace libcamera::ipa::rkisp1 {
  *
  * The gain should be adapted to the sensor specific gain code before applying.
  *
+ * \var IPAFrameContext::agc.vblank
+ * \brief Vertical blanking parameter computed by the algorithm
+ *
  * \var IPAFrameContext::agc.autoExposureEnabled
  * \brief Manual/automatic AGC state (exposure) as set by the ExposureTimeMode control
  *
@@ -307,9 +315,15 @@ namespace libcamera::ipa::rkisp1 {
  * \var IPAFrameContext::agc.meteringMode
  * \brief Metering mode as set by the AeMeteringMode control
  *
+ * \var IPAFrameContext::agc.minFrameDuration
+ * \brief Minimum frame duration as set by the FrameDurationLimits control
+ *
  * \var IPAFrameContext::agc.maxFrameDuration
  * \brief Maximum frame duration as set by the FrameDurationLimits control
  *
+ * \var IPAFrameContext::agc.frameDuration
+ * \brief The actual FrameDuration used by the algorithm for the frame
+ *
  * \var IPAFrameContext::agc.updateMetering
  * \brief Indicate if new ISP AGC metering parameters need to be applied
  *

src/ipa/rkisp1/ipa_context.h

@@ -84,6 +84,7 @@ struct IPAActiveState {
 		controls::AeConstraintModeEnum constraintMode;
 		controls::AeExposureModeEnum exposureMode;
 		controls::AeMeteringModeEnum meteringMode;
+		utils::Duration minFrameDuration;
 		utils::Duration maxFrameDuration;
 	} agc;
 
@@ -125,12 +126,15 @@ struct IPAFrameContext : public FrameContext {
 	struct {
 		uint32_t exposure;
 		double gain;
+		uint32_t vblank;
 		bool autoExposureEnabled;
 		bool autoGainEnabled;
 		controls::AeConstraintModeEnum constraintMode;
 		controls::AeExposureModeEnum exposureMode;
 		controls::AeMeteringModeEnum meteringMode;
+		utils::Duration minFrameDuration;
 		utils::Duration maxFrameDuration;
+		utils::Duration frameDuration;
 		bool updateMetering;
 		bool autoExposureModeChange;
 		bool autoGainModeChange;

src/ipa/rkisp1/rkisp1.cpp

@@ -453,10 +453,12 @@ void IPARkISP1::setControls(unsigned int frame)
 	IPAFrameContext &frameContext = context_.frameContexts.get(frame);
 	uint32_t exposure = frameContext.agc.exposure;
 	uint32_t gain = context_.camHelper->gainCode(frameContext.agc.gain);
+	uint32_t vblank = frameContext.agc.vblank;
 
 	ControlList ctrls(sensorControls_);
 	ctrls.set(V4L2_CID_EXPOSURE, static_cast<int32_t>(exposure));
 	ctrls.set(V4L2_CID_ANALOGUE_GAIN, static_cast<int32_t>(gain));
+	ctrls.set(V4L2_CID_VBLANK, static_cast<int32_t>(vblank));
 
 	setSensorControls.emit(frame, ctrls);
 }

src/libcamera/pipeline/rkisp1/rkisp1.cpp

@@ -1325,6 +1325,7 @@ int PipelineHandlerRkISP1::createCamera(MediaEntity *sensor)
 	std::unordered_map<uint32_t, DelayedControls::ControlParams> params = {
 		{ V4L2_CID_ANALOGUE_GAIN, { delays.gainDelay, false } },
 		{ V4L2_CID_EXPOSURE, { delays.exposureDelay, false } },
+		{ V4L2_CID_VBLANK, { 1, false } },
 	};
 
 	data->delayedCtrls_ =