libcamera: software_isp: Make measurement configurable

Software ISP performs performance measurement on certain part of initial
frames.  Let's make this range configurable.

For this purpose, this patch introduces new configuration options
software_isp.measure.skip and software_isp.measure.number.  Setting the
latter one to 0 disables the measurement.

Instead of the last frame, the class member and its configuration
specify the number of frames to measure.  This is easier to use for
users and doesn't require to adjust two configuration parameters when
the number of the initially skipped frames is changed.

The patch also changes the names of the class members to make them more
accurate.

Completes software ISP TODO #7.

Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

Documentation/runtime_configuration.rst

@@ -48,6 +48,9 @@ file structure:
             software_isp: # true/false
     software_isp:
       copy_input_buffer: # true/false
+      measure:
+        skip: # non-negative integer, frames to skip initially
+        number: # non-negative integer, frames to measure
 
 Configuration file example
 --------------------------
@@ -78,6 +81,9 @@ Configuration file example
              software_isp: true
      software_isp:
        copy_input_buffer: false
+       measure:
+         skip: 50
+         number: 30
 
 List of variables and configuration options
 -------------------------------------------
@@ -149,6 +155,18 @@ software_isp.copy_input_buffer
 
    Example value: ``false``
 
+software_isp.measure.skip, software_isp.measure.number
+   Define per-frame time measurement parameters in software ISP. `skip`
+   defines how many initial frames are skipped before starting the
+   measurement; `number` defines how many frames then participate in the
+   measurement.
+
+   Set `software_isp.measure.number` to 0 to disable the measurement.
+
+   Example `skip` value: ``50``
+
+   Example `number` value: ``30``
+
 Further details
 ---------------
 

src/libcamera/software_isp/TODO

@@ -71,31 +71,6 @@ per-frame buffers like we do for hardware ISPs.
 
 ---
 
-7. Performance measurement configuration
-
-> void DebayerCpu::process(FrameBuffer *input, FrameBuffer *output, DebayerParams params)
-> /* Measure before emitting signals */
-> if (measuredFrames_ < DebayerCpu::kLastFrameToMeasure &&
->     ++measuredFrames_ > DebayerCpu::kFramesToSkip) {
-> 	timespec frameEndTime = {};
-> 	clock_gettime(CLOCK_MONOTONIC_RAW, &frameEndTime);
-> 	frameProcessTime_ += timeDiff(frameEndTime, frameStartTime);
-> 	if (measuredFrames_ == DebayerCpu::kLastFrameToMeasure) {
-> 		const unsigned int measuredFrames = DebayerCpu::kLastFrameToMeasure -
-> 						    DebayerCpu::kFramesToSkip;
-> 		LOG(Debayer, Info)
-> 			<< "Processed " << measuredFrames
-> 			<< " frames in " << frameProcessTime_ / 1000 << "us, "
-> 			<< frameProcessTime_ / (1000 * measuredFrames)
-> 			<< " us/frame";
-> 	}
-> }
-
-I wonder if there would be a way to control at runtime when/how to
-perform those measurements. Maybe that's a bit overkill.
-
----
-
 8. DebayerCpu cleanups
 
 > >> class DebayerCpu : public Debayer, public Object

src/libcamera/software_isp/debayer_cpu.cpp

@@ -58,6 +58,13 @@ DebayerCpu::DebayerCpu(std::unique_ptr<SwStatsCpu> stats, const GlobalConfigurat
 	enableInputMemcpy_ =
 		configuration.option<bool>({ "software_isp", "copy_input_buffer" }).value_or(true);
 
+	skipBeforeMeasure_ = configuration.option<unsigned int>(
+						  { "software_isp", "measure", "skip" })
+				     .value_or(skipBeforeMeasure_);
+	framesToMeasure_ = configuration.option<unsigned int>(
+						{ "software_isp", "measure", "number" })
+				   .value_or(framesToMeasure_);
+
 	/* Initialize color lookup tables */
 	for (unsigned int i = 0; i < DebayerParams::kRGBLookupSize; i++) {
 		red_[i] = green_[i] = blue_[i] = i;
@@ -560,7 +567,7 @@ int DebayerCpu::configure(const StreamConfiguration &inputCfg,
 			lineBuffers_[i].resize(lineBufferLength_);
 	}
 
-	measuredFrames_ = 0;
+	encounteredFrames_ = 0;
 	frameProcessTime_ = 0;
 
 	return 0;
@@ -766,7 +773,10 @@ void DebayerCpu::process(uint32_t frame, FrameBuffer *input, FrameBuffer *output
 {
 	timespec frameStartTime;
 
-	if (measuredFrames_ < DebayerCpu::kLastFrameToMeasure) {
+	bool measure = framesToMeasure_ > 0 &&
+		       encounteredFrames_ < skipBeforeMeasure_ + framesToMeasure_ &&
+		       ++encounteredFrames_ > skipBeforeMeasure_;
+	if (measure) {
 		frameStartTime = {};
 		clock_gettime(CLOCK_MONOTONIC_RAW, &frameStartTime);
 	}
@@ -823,18 +833,15 @@ void DebayerCpu::process(uint32_t frame, FrameBuffer *input, FrameBuffer *output
 	dmaSyncers.clear();
 
 	/* Measure before emitting signals */
-	if (measuredFrames_ < DebayerCpu::kLastFrameToMeasure &&
-	    ++measuredFrames_ > DebayerCpu::kFramesToSkip) {
+	if (measure) {
 		timespec frameEndTime = {};
 		clock_gettime(CLOCK_MONOTONIC_RAW, &frameEndTime);
 		frameProcessTime_ += timeDiff(frameEndTime, frameStartTime);
-		if (measuredFrames_ == DebayerCpu::kLastFrameToMeasure) {
-			const unsigned int measuredFrames = DebayerCpu::kLastFrameToMeasure -
-							    DebayerCpu::kFramesToSkip;
+		if (encounteredFrames_ == skipBeforeMeasure_ + framesToMeasure_) {
 			LOG(Debayer, Info)
-				<< "Processed " << measuredFrames
+				<< "Processed " << framesToMeasure_
 				<< " frames in " << frameProcessTime_ / 1000 << "us, "
-				<< frameProcessTime_ / (1000 * measuredFrames)
+				<< frameProcessTime_ / (1000 * framesToMeasure_)
 				<< " us/frame";
 		}
 	}

src/libcamera/software_isp/debayer_cpu.h

@@ -161,11 +161,10 @@ private:
 	unsigned int xShift_; /* Offset of 0/1 applied to window_.x */
 	bool enableInputMemcpy_;
 	bool swapRedBlueGains_;
-	unsigned int measuredFrames_;
+	unsigned int encounteredFrames_;
 	int64_t frameProcessTime_;
-	/* Skip 30 frames for things to stabilize then measure 30 frames */
-	static constexpr unsigned int kFramesToSkip = 30;
-	static constexpr unsigned int kLastFrameToMeasure = 60;
+	unsigned int skipBeforeMeasure_ = 30;
+	unsigned int framesToMeasure_ = 30;
 };
 
 } /* namespace libcamera */