[libcamera-devel] [PATCH 2/3] src: ipa: raspberrypi: Improve behaviour when AE disabled

[David Plowman]

AE/AGC "disabled" is now implemented by leaving it running but fixing
the exposure/gain to the last values we requested. This behaves better
when, for example, a fixed shutter or gain is then specified - the
other value remains fixed and doesn't start floating again.

Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
---
 src/ipa/raspberrypi/raspberrypi.cpp | 48 ++++++++++++++++++-----------
 1 file changed, 30 insertions(+), 18 deletions(-)

diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
index 9853a343..30516665 100644
--- a/src/ipa/raspberrypi/raspberrypi.cpp
+++ b/src/ipa/raspberrypi/raspberrypi.cpp
@@ -67,7 +67,8 @@ public:
 	IPARPi()
 		: lastMode_({}), controller_(), controllerInit_(false),
 		  frameCount_(0), checkCount_(0), mistrustCount_(0),
-		  lsTable_(nullptr)
+		  lsTable_(nullptr),
+		  lastShutter_(0), lastGain_(0)
 	{
 	}
 
@@ -145,6 +146,10 @@ private:
 	/* LS table allocation passed in from the pipeline handler. */
 	FileDescriptor lsTableHandle_;
 	void *lsTable_;
+
+	/* For enabling/disabling the AEC/AGC algorithm. */
+	uint32_t lastShutter_;
+	float lastGain_;
 };
 
 int IPARPi::init(const IPASettings &settings)
@@ -493,12 +498,22 @@ void IPARPi::queueRequest(const ControlList &controls)
 
 		switch (ctrl.first) {
 		case controls::AE_ENABLE: {
-			RPiController::Algorithm *agc = controller_.GetAlgorithm("agc");
+			RPiController::AgcAlgorithm *agc = dynamic_cast<RPiController::AgcAlgorithm *>(
+				controller_.GetAlgorithm("agc"));
 			ASSERT(agc);
-			if (ctrl.second.get<bool>() == false)
-				agc->Pause();
-			else
-				agc->Resume();
+
+			/*
+			 * We always run the AGC even if it's "disabled".
+			 * Both exposure and gain are "fixed" to the last
+			 * values it produced.
+			 */
+			if (ctrl.second.get<bool>() == false) {
+				agc->SetFixedShutter(lastShutter_);
+				agc->SetFixedAnalogueGain(lastGain_);
+			} else {
+				agc->SetFixedShutter(0);
+				agc->SetFixedAnalogueGain(0);
+			}
 
 			libcameraMetadata_.set(controls::AeEnable, ctrl.second.get<bool>());
 			break;
@@ -510,13 +525,10 @@ void IPARPi::queueRequest(const ControlList &controls)
 			ASSERT(agc);
 
 			/* This expects units of micro-seconds. */
-			agc->SetFixedShutter(ctrl.second.get<int32_t>());
+			int32_t shutter = ctrl.second.get<int32_t>();
+			agc->SetFixedShutter(shutter);
 
-			/* For the manual values to take effect, AGC must be unpaused. */
-			if (agc->IsPaused())
-				agc->Resume();
-
-			libcameraMetadata_.set(controls::ExposureTime, ctrl.second.get<int32_t>());
+			libcameraMetadata_.set(controls::ExposureTime, shutter);
 			break;
 		}
 
@@ -524,14 +536,11 @@ void IPARPi::queueRequest(const ControlList &controls)
 			RPiController::AgcAlgorithm *agc = dynamic_cast<RPiController::AgcAlgorithm *>(
 				controller_.GetAlgorithm("agc"));
 			ASSERT(agc);
-			agc->SetFixedAnalogueGain(ctrl.second.get<float>());
 
-			/* For the manual values to take effect, AGC must be unpaused. */
-			if (agc->IsPaused())
-				agc->Resume();
+			float gain = ctrl.second.get<float>();
+			agc->SetFixedAnalogueGain(gain);
 
-			libcameraMetadata_.set(controls::AnalogueGain,
-					       ctrl.second.get<float>());
+			libcameraMetadata_.set(controls::AnalogueGain, gain);
 			break;
 		}
 
@@ -861,6 +870,9 @@ void IPARPi::applyAWB(const struct AwbStatus *awbStatus, ControlList &ctrls)
 
 void IPARPi::applyAGC(const struct AgcStatus *agcStatus, ControlList &ctrls)
 {
+	lastShutter_ = agcStatus->shutter_time;
+	lastGain_ = agcStatus->analogue_gain;
+
 	int32_t gainCode = helper_->GainCode(agcStatus->analogue_gain);
 	int32_t exposureLines = helper_->ExposureLines(agcStatus->shutter_time);
 
-- 
2.20.1