[PATCH 1/3] ipa: ipu3: Refer to integration time instead of shutter speed

[Daniel Scally]

Within the IPU3 IPA module there are multiple references to min and
max shutter speeds. In calculation and usage however those variables
reflect integration time rather than shutter speed - this difference
in terminology is particularly problematic because the minimum
shutter speed is equivalent to the maximum integration time.

Replace references to shutter speed with integration time.

Signed-off-by: Daniel Scally <dan.scally at ideasonboard.com>
---
 src/ipa/ipu3/algorithms/agc.cpp | 12 ++++++------
 src/ipa/ipu3/algorithms/agc.h   |  4 ++--
 src/ipa/ipu3/ipa_context.cpp    |  8 ++++----
 src/ipa/ipu3/ipa_context.h      |  4 ++--
 src/ipa/ipu3/ipu3.cpp           |  8 ++++----
 5 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/src/ipa/ipu3/algorithms/agc.cpp b/src/ipa/ipu3/algorithms/agc.cpp
index 46fc3b33..a59b73fb 100644
--- a/src/ipa/ipu3/algorithms/agc.cpp
+++ b/src/ipa/ipu3/algorithms/agc.cpp
@@ -51,7 +51,7 @@ LOG_DEFINE_CATEGORY(IPU3Agc)
 static constexpr double kMinAnalogueGain = 1.0;
 
 /* \todo Honour the FrameDurationLimits control instead of hardcoding a limit */
-static constexpr utils::Duration kMaxShutterSpeed = 60ms;
+static constexpr utils::Duration kMaxIntegrationTime = 60ms;
 
 /* Histogram constants */
 static constexpr uint32_t knumHistogramBins = 256;
@@ -71,7 +71,7 @@ static constexpr uint32_t kNumStartupFrames = 10;
 static constexpr double kRelativeLuminanceTarget = 0.16;
 
 Agc::Agc()
-	: minShutterSpeed_(0s), maxShutterSpeed_(0s)
+	: minIntegrationTime_(0s), maxIntegrationTime_(0s)
 {
 }
 
@@ -114,9 +114,9 @@ int Agc::configure(IPAContext &context,
 	stride_ = configuration.grid.stride;
 	bdsGrid_ = configuration.grid.bdsGrid;
 
-	minShutterSpeed_ = configuration.agc.minShutterSpeed;
-	maxShutterSpeed_ = std::min(configuration.agc.maxShutterSpeed,
-				    kMaxShutterSpeed);
+	minIntegrationTime_ = configuration.agc.minIntegrationTime;
+	maxIntegrationTime_ = std::min(configuration.agc.maxIntegrationTime,
+				       kMaxIntegrationTime);
 
 	minAnalogueGain_ = std::max(configuration.agc.minAnalogueGain, kMinAnalogueGain);
 	maxAnalogueGain_ = configuration.agc.maxAnalogueGain;
@@ -129,7 +129,7 @@ int Agc::configure(IPAContext &context,
 	context.activeState.agc.exposureMode = exposureModeHelpers().begin()->first;
 
 	/* \todo Run this again when FrameDurationLimits is passed in */
-	configureExposureModeHelpers(minShutterSpeed_, maxShutterSpeed_,
+	configureExposureModeHelpers(minIntegrationTime_, maxIntegrationTime_,
 				     minAnalogueGain_, maxAnalogueGain_);
 
 	resetFrameCount();
diff --git a/src/ipa/ipu3/algorithms/agc.h b/src/ipa/ipu3/algorithms/agc.h
index 945d1846..631dea52 100644
--- a/src/ipa/ipu3/algorithms/agc.h
+++ b/src/ipa/ipu3/algorithms/agc.h
@@ -42,8 +42,8 @@ private:
 	Histogram parseStatistics(const ipu3_uapi_stats_3a *stats,
 				  const ipu3_uapi_grid_config &grid);
 
-	utils::Duration minShutterSpeed_;
-	utils::Duration maxShutterSpeed_;
+	utils::Duration minIntegrationTime_;
+	utils::Duration maxIntegrationTime_;
 
 	double minAnalogueGain_;
 	double maxAnalogueGain_;
diff --git a/src/ipa/ipu3/ipa_context.cpp b/src/ipa/ipu3/ipa_context.cpp
index c4fb5642..72f7cec9 100644
--- a/src/ipa/ipu3/ipa_context.cpp
+++ b/src/ipa/ipu3/ipa_context.cpp
@@ -92,11 +92,11 @@ namespace libcamera::ipa::ipu3 {
  * \var IPASessionConfiguration::agc
  * \brief AGC parameters configuration of the IPA
  *
- * \var IPASessionConfiguration::agc.minShutterSpeed
- * \brief Minimum shutter speed supported with the configured sensor
+ * \var IPASessionConfiguration::agc.minIntegrationTime
+ * \brief Minimum integration time supported with the configured sensor
  *
- * \var IPASessionConfiguration::agc.maxShutterSpeed
- * \brief Maximum shutter speed supported with the configured sensor
+ * \var IPASessionConfiguration::agc.maxIntegrationTime
+ * \brief Maximum integration time supported with the configured sensor
  *
  * \var IPASessionConfiguration::agc.minAnalogueGain
  * \brief Minimum analogue gain supported with the configured sensor
diff --git a/src/ipa/ipu3/ipa_context.h b/src/ipa/ipu3/ipa_context.h
index a92cb6ce..6b1ffdd1 100644
--- a/src/ipa/ipu3/ipa_context.h
+++ b/src/ipa/ipu3/ipa_context.h
@@ -33,8 +33,8 @@ struct IPASessionConfiguration {
 	} af;
 
 	struct {
-		utils::Duration minShutterSpeed;
-		utils::Duration maxShutterSpeed;
+		utils::Duration minIntegrationTime;
+		utils::Duration maxIntegrationTime;
 		double minAnalogueGain;
 		double maxAnalogueGain;
 	} agc;
diff --git a/src/ipa/ipu3/ipu3.cpp b/src/ipa/ipu3/ipu3.cpp
index 4809eb60..f13cc394 100644
--- a/src/ipa/ipu3/ipu3.cpp
+++ b/src/ipa/ipu3/ipu3.cpp
@@ -217,13 +217,13 @@ void IPAIPU3::updateSessionConfiguration(const ControlInfoMap &sensorControls)
 
 	/*
 	 * When the AGC computes the new exposure values for a frame, it needs
-	 * to know the limits for shutter speed and analogue gain.
+	 * to know the limits for integration time and analogue gain.
 	 * As it depends on the sensor, update it with the controls.
 	 *
-	 * \todo take VBLANK into account for maximum shutter speed
+	 * \todo take VBLANK into account for maximum integration time
 	 */
-	context_.configuration.agc.minShutterSpeed = minExposure * context_.configuration.sensor.lineDuration;
-	context_.configuration.agc.maxShutterSpeed = maxExposure * context_.configuration.sensor.lineDuration;
+	context_.configuration.agc.minIntegrationTime = minExposure * context_.configuration.sensor.lineDuration;
+	context_.configuration.agc.maxIntegrationTime = maxExposure * context_.configuration.sensor.lineDuration;
 	context_.configuration.agc.minAnalogueGain = camHelper_->gain(minGain);
 	context_.configuration.agc.maxAnalogueGain = camHelper_->gain(maxGain);
 }
-- 
2.34.1