[PATCH v2 19/19] libcamera: software_isp: Update black level only on exposure changes

[Milan Zamazal]

The black level is likely to get updated, if ever, only after exposure
or gain changes.  Don't compute its possible updates if exposure and
gain are unchanged.

It's probably not worth trying to implement something more
sophisticated.  Better to spend the effort on supporting tuning files.

Signed-off-by: Milan Zamazal <mzamazal at redhat.com>
---
 src/ipa/simple/algorithms/blc.cpp | 9 ++++++++-
 src/ipa/simple/algorithms/blc.h   | 4 ++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/src/ipa/simple/algorithms/blc.cpp b/src/ipa/simple/algorithms/blc.cpp
index 49f13682..8f7828d9 100644
--- a/src/ipa/simple/algorithms/blc.cpp
+++ b/src/ipa/simple/algorithms/blc.cpp
@@ -30,10 +30,15 @@ int BlackLevel::init(IPAContext &context,
 
 void BlackLevel::process(IPAContext &context,
 			 [[maybe_unused]] const uint32_t frame,
-			 [[maybe_unused]] IPAFrameContext &frameContext,
+			 IPAFrameContext &frameContext,
 			 const SwIspStats *stats,
 			 [[maybe_unused]] ControlList &metadata)
 {
+	if (frameContext.sensor.exposure == exposure_ &&
+	    frameContext.sensor.gain == gain_) {
+		return;
+	}
+
 	const SwIspStats::Histogram &histogram = stats->yHistogram;
 
 	/*
@@ -54,6 +59,8 @@ void BlackLevel::process(IPAContext &context,
 		if (seen >= pixelThreshold) {
 			context.activeState.black.level =
 				static_cast<double>(i) / SwIspStats::kYHistogramSize;
+			exposure_ = frameContext.sensor.exposure;
+			gain_ = frameContext.sensor.gain;
 			LOG(IPASoftBL, Debug)
 				<< "Auto-set black level: "
 				<< i << "/" << SwIspStats::kYHistogramSize
diff --git a/src/ipa/simple/algorithms/blc.h b/src/ipa/simple/algorithms/blc.h
index c8b8d92d..4ddd2c94 100644
--- a/src/ipa/simple/algorithms/blc.h
+++ b/src/ipa/simple/algorithms/blc.h
@@ -30,6 +30,10 @@ public:
 		     IPAFrameContext &frameContext,
 		     const SwIspStats *stats,
 		     ControlList &metadata) override;
+
+private:
+	uint32_t exposure_;
+	double gain_;
 };
 
 } /* namespace ipa::soft::algorithms */
-- 
2.44.1