[libcamera-devel] [PATCH v4 13/14] ipa: ipu3: agc: Remove unused variables

[Jean-Michel Hautbois]

We currently control the exposure value by the shutter speed and the
analogue gain. We can't use the digital gain to have more than the
maximum exposure value calculated because we are not controlling it.

Remove unused code associated with this digital gain.

Signed-off-by: Jean-Michel Hautbois <jeanmichel.hautbois at ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham at ideasonboard.com>
---
 src/ipa/ipu3/algorithms/agc.cpp | 19 +++----------------
 src/ipa/ipu3/algorithms/agc.h   |  2 --
 2 files changed, 3 insertions(+), 18 deletions(-)

diff --git a/src/ipa/ipu3/algorithms/agc.cpp b/src/ipa/ipu3/algorithms/agc.cpp
index feee7939..74e94544 100644
--- a/src/ipa/ipu3/algorithms/agc.cpp
+++ b/src/ipa/ipu3/algorithms/agc.cpp
@@ -42,8 +42,7 @@ static constexpr double kEvGainTarget = 0.5;
 Agc::Agc()
 	: frameCount_(0), lastFrame_(0), iqMean_(0.0), lineDuration_(0s),
 	  minExposureLines_(0), maxExposureLines_(0), filteredExposure_(0s),
-	  filteredExposureNoDg_(0s), currentExposure_(0s),
-	  currentExposureNoDg_(0s), prevExposureValue_(0s)
+	  currentExposure_(0s), prevExposureValue_(0s)
 {
 }
 
@@ -102,7 +101,6 @@ void Agc::filterExposure()
 	if (filteredExposure_ == 0s) {
 		/* DG stands for digital gain.*/
 		filteredExposure_ = currentExposure_;
-		filteredExposureNoDg_ = currentExposureNoDg_;
 	} else {
 		/*
 		 * If we are close to the desired result, go faster to avoid making
@@ -115,18 +113,8 @@ void Agc::filterExposure()
 
 		filteredExposure_ = speed * currentExposure_ +
 				filteredExposure_ * (1.0 - speed);
-		filteredExposureNoDg_ = speed * currentExposureNoDg_ +
-				filteredExposureNoDg_ * (1.0 - speed);
 	}
-	/*
-	 * We can't let the no_dg exposure deviate too far below the
-	 * total exposure, as there might not be enough digital gain available
-	 * in the ISP to hide it (which will cause nasty oscillation).
-	 */
-	double fastReduceThreshold = 0.4;
-	if (filteredExposureNoDg_ <
-	    filteredExposure_ * fastReduceThreshold)
-		filteredExposureNoDg_ = filteredExposure_ * fastReduceThreshold;
+
 	LOG(IPU3Agc, Debug) << "After filtering, total_exposure " << filteredExposure_;
 }
 
@@ -151,8 +139,7 @@ void Agc::lockExposureGain(uint32_t &exposure, double &analogueGain)
 
 	/* extracted from Rpi::Agc::computeTargetExposure */
 	utils::Duration currentShutter = exposure * lineDuration_;
-	currentExposureNoDg_ = currentShutter * analogueGain;
-	LOG(IPU3Agc, Debug) << "Actual total exposure " << currentExposureNoDg_
+	LOG(IPU3Agc, Debug) << "Actual total exposure " << currentShutter * analogueGain
 			    << " Shutter speed " << currentShutter
 			    << " Gain " << analogueGain
 			    << " Needed ev gain " << evGain;
diff --git a/src/ipa/ipu3/algorithms/agc.h b/src/ipa/ipu3/algorithms/agc.h
index 2ae88e9f..ad133b98 100644
--- a/src/ipa/ipu3/algorithms/agc.h
+++ b/src/ipa/ipu3/algorithms/agc.h
@@ -46,9 +46,7 @@ private:
 	uint32_t maxExposureLines_;
 
 	utils::Duration filteredExposure_;
-	utils::Duration filteredExposureNoDg_;
 	utils::Duration currentExposure_;
-	utils::Duration currentExposureNoDg_;
 	utils::Duration prevExposureValue_;
 
 	uint32_t stride_;
-- 
2.32.0