ipa: raspberrypi: agc: Fix digital gain calculation for manual mode

The digital gain calculation uses a total exposure value computed with the
current AGC state. However, this is wrong in the case of manual shutter/gain
controls, as the total exposure value used must be the value computed when the
AGC sent the manual shutter/gain controls to the pipeline handler to action.

To fix this, the IPA now adds the historical AgcStatus structure to the metadata
(tagged with "agc.delayed_status"). This historical AgcStatus structure contains
the total exposure value calculated when the AGC sent the manual shutter/gain
controls to the pipeline handler.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: David Plowman <david.plowman@raspberrypi.com>
Tested-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

2 files changed, 19 insertions, 2 deletions

diff --git a/src/ipa/raspberrypi/controller/rpi/agc.cpp b/src/ipa/raspberrypi/controller/rpi/agc.cpp
index a30e50c1..46dcc81a 100644
--- a/src/ipa/raspberrypi/controller/rpi/agc.cpp
+++ b/src/ipa/raspberrypi/controller/rpi/agc.cpp
@@ -403,6 +403,12 @@ void Agc::switchMode(CameraMode const &cameraMode,
 
 void Agc::prepare(Metadata *imageMetadata)
 {
+	Duration totalExposureValue = status_.totalExposureValue;
+	AgcStatus delayedStatus;
+
+	if (!imageMetadata->get("agc.delayed_status", delayedStatus))
+		totalExposureValue = delayedStatus.totalExposureValue;
+
 	status_.digitalGain = 1.0;
 	fetchAwbStatus(imageMetadata); /* always fetch it so that Process knows it's been done */
 
@@ -413,8 +419,8 @@ void Agc::prepare(Metadata *imageMetadata)
 			Duration actualExposure = deviceStatus.shutterSpeed *
 						  deviceStatus.analogueGain;
 			if (actualExposure) {
-				status_.digitalGain = status_.totalExposureValue / actualExposure;
-				LOG(RPiAgc, Debug) << "Want total exposure " << status_.totalExposureValue;
+				status_.digitalGain = totalExposureValue / actualExposure;
+				LOG(RPiAgc, Debug) << "Want total exposure " << totalExposureValue;
 				/*
 				 * Never ask for a gain < 1.0, and also impose
 				 * some upper limit. Make it customisable?
diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
index 3157805c..0f914f84 100644
--- a/src/ipa/raspberrypi/raspberrypi.cpp
+++ b/src/ipa/raspberrypi/raspberrypi.cpp
@@ -1031,6 +1031,17 @@ void IPARPi::prepareISP(const ISPConfig &data)
 	}
 
 	/*
+	 * AGC wants to know the algorithm status from the time it actioned the
+	 * sensor exposure/gain changes. So fetch it from the metadata list
+	 * indexed by the IPA cookie returned, and put it in the current frame
+	 * metadata.
+	 */
+	AgcStatus agcStatus;
+	RPiController::Metadata &delayedMetadata = rpiMetadata_[data.delayContext];
+	if (!delayedMetadata.get<AgcStatus>("agc.status", agcStatus))
+		rpiMetadata.set("agc.delayed_status", agcStatus);
+
+	/*
 	 * This may overwrite the DeviceStatus using values from the sensor
 	 * metadata, and may also do additional custom processing.
 	 */