[v4,18/21] ipa: mali-c55: agc: Quantise the ISP Digital Gain
diff mbox series

Message ID 20251114005428.90024-19-kieran.bingham@ideasonboard.com
State New
Headers show
Series
  • libipa: Introduce a Quantized type
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Commit Message

Kieran Bingham Nov. 14, 2025, 12:54 a.m. UTC
The Mali-C55 ISP has a digital gain block which allows setting gain in Q5.8
format, a range of 0.0 to (very nearly) 32.0.

Convert usage to the new UQ5_8 FixedPoint Quantised type which will
support the conversion, clamping and quantisation so that the metadata
and debug prints can now report the effective gain applied instead of
the potentially inaccurate float.

As the UQ5_8 type already clamps values, remove the explicit clamping.
This removes the clamping to a minimum of 1.0 gain, so we rely on
calculateNewEv to provide a valid gain.

Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
---
 src/ipa/mali-c55/algorithms/agc.cpp | 20 ++++++++++----------
 src/ipa/mali-c55/ipa_context.h      |  6 +++---
 2 files changed, 13 insertions(+), 13 deletions(-)

Patch
diff mbox series

diff --git a/src/ipa/mali-c55/algorithms/agc.cpp b/src/ipa/mali-c55/algorithms/agc.cpp
index f60fddac3f04..3f10b237f581 100644
--- a/src/ipa/mali-c55/algorithms/agc.cpp
+++ b/src/ipa/mali-c55/algorithms/agc.cpp
@@ -38,8 +38,8 @@  static constexpr unsigned int kNumHistogramBins = 256;
  * format, a range of 0.0 to (very nearly) 32.0. We clamp from 1.0 to the actual
  * max value which is 8191 * 2^-8.
  */
-static constexpr double kMinDigitalGain = 1.0;
-static constexpr double kMaxDigitalGain = 31.99609375;
+static constexpr float kMinDigitalGain = 1.0;
+static constexpr float kMaxDigitalGain = UQ5_8::TraitsType::max;
 
 uint32_t AgcStatistics::decodeBinValue(uint16_t binVal)
 {
@@ -236,7 +236,7 @@  void Agc::queueRequest(IPAContext &context, const uint32_t frame,
 		agc.manual.ispGain = *digitalGain;
 
 		LOG(MaliC55Agc, Debug)
-			<< "Digital gain set to " << agc.manual.ispGain
+			<< "Digital gain set to " << agc.manual.ispGain.value()
 			<< " on request sequence " << frame;
 	}
 }
@@ -245,7 +245,7 @@  size_t Agc::fillGainParamBlock(IPAContext &context, IPAFrameContext &frameContex
 			       mali_c55_params_block block)
 {
 	IPAActiveState &activeState = context.activeState;
-	double gain;
+	UQ5_8 gain;
 
 	if (activeState.agc.autoEnabled)
 		gain = activeState.agc.automatic.ispGain;
@@ -256,7 +256,7 @@  size_t Agc::fillGainParamBlock(IPAContext &context, IPAFrameContext &frameContex
 	block.header->flags = MALI_C55_PARAM_BLOCK_FL_NONE;
 	block.header->size = sizeof(struct mali_c55_params_digital_gain);
 
-	block.digital_gain->gain = floatingToFixedPoint<5, 8, uint16_t, double>(gain);
+	block.digital_gain->gain = gain.quantized();
 	frameContext.agc.ispGain = gain;
 
 	return block.header->size;
@@ -376,7 +376,7 @@  void Agc::process(IPAContext &context,
 	 */
 	uint32_t exposure = frameContext.agc.exposure;
 	double analogueGain = frameContext.agc.sensorGain;
-	double digitalGain = frameContext.agc.ispGain;
+	double digitalGain = frameContext.agc.ispGain.value();
 	double totalGain = analogueGain * digitalGain;
 	utils::Duration currentShutter = exposure * configuration.sensor.lineDuration;
 	utils::Duration effectiveExposureValue = currentShutter * totalGain;
@@ -388,19 +388,19 @@  void Agc::process(IPAContext &context,
 			       activeState.agc.exposureMode, statistics_.yHist,
 			       effectiveExposureValue);
 
-	dGain = std::clamp(dGain, kMinDigitalGain, kMaxDigitalGain);
+	UQ5_8 dGainQ = static_cast<float>(dGain);
 
 	LOG(MaliC55Agc, Debug)
 		<< "Divided up shutter, analogue gain and digital gain are "
-		<< shutterTime << ", " << aGain << " and " << dGain;
+		<< shutterTime << ", " << aGain << " and " << dGainQ.value();
 
 	activeState.agc.automatic.exposure = shutterTime / configuration.sensor.lineDuration;
 	activeState.agc.automatic.sensorGain = aGain;
-	activeState.agc.automatic.ispGain = dGain;
+	activeState.agc.automatic.ispGain = dGainQ;
 
 	metadata.set(controls::ExposureTime, currentShutter.get<std::micro>());
 	metadata.set(controls::AnalogueGain, frameContext.agc.sensorGain);
-	metadata.set(controls::DigitalGain, frameContext.agc.ispGain);
+	metadata.set(controls::DigitalGain, frameContext.agc.ispGain.value());
 	metadata.set(controls::ColourTemperature, context.activeState.agc.temperatureK);
 }
 
diff --git a/src/ipa/mali-c55/ipa_context.h b/src/ipa/mali-c55/ipa_context.h
index 86d060a731cb..2db3fdf9e5cf 100644
--- a/src/ipa/mali-c55/ipa_context.h
+++ b/src/ipa/mali-c55/ipa_context.h
@@ -41,12 +41,12 @@  struct IPAActiveState {
 		struct {
 			uint32_t exposure;
 			double sensorGain;
-			double ispGain;
+			UQ5_8 ispGain;
 		} automatic;
 		struct {
 			uint32_t exposure;
 			double sensorGain;
-			double ispGain;
+			UQ5_8 ispGain;
 		} manual;
 		bool autoEnabled;
 		uint32_t constraintMode;
@@ -64,7 +64,7 @@  struct IPAFrameContext : public FrameContext {
 	struct {
 		uint32_t exposure;
 		double sensorGain;
-		double ispGain;
+		UQ5_8 ispGain;
 	} agc;
 
 	struct {