libcamera: software_isp: Add manual exposure control

Signed-off-by: Vasiliy Doylov <nekocwd@mainlining.org>

src/ipa/simple/algorithms/agc.cpp

@@ -46,6 +46,8 @@ int Agc::init(IPAContext &context,
 {
 	context.ctrlMap[&controls::AeEnable] = ControlInfo(false, true, true);
 	context.ctrlMap[&controls::Brightness] = ControlInfo(0.0f, 2.0f, 1.0f);
+	context.ctrlMap[&controls::ExposureValue] = ControlInfo(0.0f, 0.5f, 1.0f);
+
 	return 0;
 }
 
@@ -65,6 +67,7 @@ void Agc::queueRequest(typename Module::Context &context,
 {
 	const auto &brightness = controls.get(controls::Brightness);
 	const auto &ae_enabled = controls.get(controls::AeEnable);
+	const auto &exposure_value = controls.get(controls::ExposureValue);
 	if (brightness.has_value()) {
 		context.activeState.knobs.brightness = brightness;
 		LOG(IPASoftExposure, Debug) << "Setting brightness to " << brightness.value();
@@ -73,6 +76,10 @@ void Agc::queueRequest(typename Module::Context &context,
 		context.activeState.knobs.ae_enabled = ae_enabled;
 		LOG(IPASoftExposure, Debug) << "Setting ae_enable to " << ae_enabled.value();
 	}
+	if (exposure_value.has_value()) {
+		context.activeState.knobs.exposure_value = exposure_value.value();
+		LOG(IPASoftExposure, Debug) << "Setting exposure value to " << exposure_value.value();
+	}
 }
 
 void Agc::updateExposure(IPAContext &context, IPAFrameContext &frameContext, double exposureMSV)
@@ -140,13 +147,16 @@ void Agc::process(IPAContext &context,
 		  ControlList &metadata)
 {
 	const auto ae_enable = context.activeState.knobs.ae_enabled.value_or(true);
-	if (!ae_enable)
-		return;
 
+	if (!ae_enable)
+		frameContext.sensor.exposure = (int32_t)( context.activeState.knobs.exposure_value.value_or(0.5) * (context.configuration.agc.exposureMax - context.configuration.agc.exposureMin));
 	utils::Duration exposureTime =
 		context.configuration.agc.lineDuration * frameContext.sensor.exposure;
 	metadata.set(controls::ExposureTime, exposureTime.get<std::micro>());
 	metadata.set(controls::AnalogueGain, frameContext.sensor.gain);
+	LOG(IPASoftExposure, Debug) << "Setting exposure value to " << frameContext.sensor.exposure;
+	if (!ae_enable)
+		return;
 
 	/*
 	 * Calculate Mean Sample Value (MSV) according to formula from:

src/ipa/simple/ipa_context.h

@@ -71,6 +71,8 @@ struct IPAActiveState {
 		std::optional<double> brightness;
 		/* 0..1 range, 1 = normal */
 		std::optional<bool> ae_enabled;
+		/* 0..1 range, 0.5 = normal */
+		std::optional<double> exposure_value;
 		/* 0..100 range, 50.0 = normal */
 		std::optional<double> focus_pos;
 	} knobs;