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ipa: mali-c55: agc: Quantise the ISP Digital Gain

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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 UQ<5, 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.

Reviewed-by: Isaac Scott <isaac.scott@ideasonboard.com>
Reviewed-by: Stefan Klug <stefan.klug@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
This commit is contained in:
Kieran Bingham
2026-02-19 15:05:14 +00:00
parent 3d4e0446af
commit 8896ca13f1
2 changed files with 15 additions and 16 deletions
Download Patch File Download Diff File Expand all files Collapse all files

25
src/ipa/mali-c55/algorithms/agc.cpp
View File

@@ -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 = UQ<5, 8>::TraitsType::max;
uint32_t AgcStatistics::decodeBinValue(uint16_t binVal)
{
@@ -139,10 +139,7 @@ int Agc::init(IPAContext &context, const YamlObject &tuningData)
context.ctrlMap[&controls::AeEnable] = ControlInfo(false, true);
context.ctrlMap[&controls::DigitalGain] = ControlInfo(
static_cast<float>(kMinDigitalGain),
static_cast<float>(kMaxDigitalGain),
static_cast<float>(kMinDigitalGain)
);
kMinDigitalGain, kMaxDigitalGain, kMinDigitalGain);
context.ctrlMap.merge(controls());
return 0;
@@ -245,7 +242,7 @@ void Agc::fillGainParamBlock(IPAContext &context, IPAFrameContext &frameContext,
MaliC55Params *params)
{
IPAActiveState &activeState = context.activeState;
double gain;
UQ<5, 8> gain;
if (activeState.agc.autoEnabled)
gain = activeState.agc.automatic.ispGain;
@@ -253,7 +250,7 @@ void Agc::fillGainParamBlock(IPAContext &context, IPAFrameContext &frameContext,
gain = activeState.agc.manual.ispGain;
auto block = params->block<MaliC55Blocks::Dgain>();
block->gain = floatingToFixedPoint<5, 8, uint16_t, double>(gain);
block->gain = gain.quantized();
frameContext.agc.ispGain = gain;
}
@@ -358,7 +355,7 @@ 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;
@@ -370,19 +367,21 @@ void Agc::process(IPAContext &context,
activeState.agc.exposureMode, statistics_.yHist,
effectiveExposureValue);
dGain = std::clamp(dGain, kMinDigitalGain, kMaxDigitalGain);
UQ<5, 8> dGainQ = std::clamp(static_cast<float>(dGain),
kMinDigitalGain,
kMaxDigitalGain);
LOG(MaliC55Agc, Debug)
<< "Divided up shutter, analogue gain and digital gain are "
<< shutterTime << ", " << aGain << " and " << dGain;
<< shutterTime << ", " << aGain << " and " << dGainQ;
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);
}

6
src/ipa/mali-c55/ipa_context.h
View File

@@ -41,12 +41,12 @@ struct IPAActiveState {
struct {
uint32_t exposure;
double sensorGain;
double ispGain;
UQ<5, 8> ispGain;
} automatic;
struct {
uint32_t exposure;
double sensorGain;
double ispGain;
UQ<5, 8> ispGain;
} manual;
bool autoEnabled;
uint32_t constraintMode;
@@ -64,7 +64,7 @@ struct IPAFrameContext : public FrameContext {
struct {
uint32_t exposure;
double sensorGain;
double ispGain;
UQ<5, 8> ispGain;
} agc;
struct {