ipa: raspberrypi: Pass the maximum allowable shutter speed into the AGC

In order to provide an optimal split between shutter speed and gain, the
AGC must know the maximum allowable shutter speed, as limited by the
maximum frame duration (either application provided or the default).

Add a new API function, SetMaxShutter, to the AgcAlgorithm class. The
IPA provides the maximum shutter speed for AGC calculations. This
applies to both the manual and auto AGC modes.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Reviewed-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 12 insertions, 0 deletions

diff --git a/src/ipa/raspberrypi/raspberrypi.cpp b/src/ipa/raspberrypi/raspberrypi.cpp
index 85aee6f7..ff14cfc4 100644
--- a/src/ipa/raspberrypi/raspberrypi.cpp
+++ b/src/ipa/raspberrypi/raspberrypi.cpp
@@ -1065,6 +1065,18 @@ void IPARPi::applyFrameDurations(double minFrameDuration, double maxFrameDuratio
 	libcameraMetadata_.set(controls::FrameDurations,
 			       { static_cast<int64_t>(minFrameDuration_),
 				 static_cast<int64_t>(maxFrameDuration_) });
+
+	/*
+	 * Calculate the maximum exposure time possible for the AGC to use.
+	 * GetVBlanking() will update maxShutter with the largest exposure
+	 * value possible.
+	 */
+	double maxShutter = std::numeric_limits<double>::max();
+	helper_->GetVBlanking(maxShutter, minFrameDuration_, maxFrameDuration_);
+
+	RPiController::AgcAlgorithm *agc = dynamic_cast<RPiController::AgcAlgorithm *>(
+		controller_.GetAlgorithm("agc"));
+	agc->SetMaxShutter(maxShutter);
 }
 
 void IPARPi::applyAGC(const struct AgcStatus *agcStatus, ControlList &ctrls)