[libcamera-devel] [PATCH v3 2/6] src: ipa: raspberrypi: agc: Add GetConvergenceFrames method to AGC base class

[David Plowman]

We add a GetConvergenceFrames method to the AgcAlgorithm class which
can be called when the AGC is started from scratch. It suggests how
many frames should be dropped before displaying any (while the AGC
converges).

The Raspberry Pi specific implementation makes this customisable from
the tuning file.

Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
Reviewed-by: Naushir Patuck <naush at raspberrypi.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart at ideasonboard.com>
---
 src/ipa/raspberrypi/controller/agc_algorithm.hpp |  1 +
 src/ipa/raspberrypi/controller/rpi/agc.cpp       | 11 +++++++++++
 src/ipa/raspberrypi/controller/rpi/agc.hpp       |  2 ++
 3 files changed, 14 insertions(+)

diff --git a/src/ipa/raspberrypi/controller/agc_algorithm.hpp b/src/ipa/raspberrypi/controller/agc_algorithm.hpp
index b4ea54fb..981f1de2 100644
--- a/src/ipa/raspberrypi/controller/agc_algorithm.hpp
+++ b/src/ipa/raspberrypi/controller/agc_algorithm.hpp
@@ -15,6 +15,7 @@ class AgcAlgorithm : public Algorithm
 public:
 	AgcAlgorithm(Controller *controller) : Algorithm(controller) {}
 	// An AGC algorithm must provide the following:
+	virtual unsigned int GetConvergenceFrames() const = 0;
 	virtual void SetEv(double ev) = 0;
 	virtual void SetFlickerPeriod(double flicker_period) = 0;
 	virtual void SetFixedShutter(double fixed_shutter) = 0; // microseconds
diff --git a/src/ipa/raspberrypi/controller/rpi/agc.cpp b/src/ipa/raspberrypi/controller/rpi/agc.cpp
index 9da18c31..eddd1684 100644
--- a/src/ipa/raspberrypi/controller/rpi/agc.cpp
+++ b/src/ipa/raspberrypi/controller/rpi/agc.cpp
@@ -142,6 +142,7 @@ void AgcConfig::Read(boost::property_tree::ptree const &params)
 	Y_target.Read(params.get_child("y_target"));
 	speed = params.get<double>("speed", 0.2);
 	startup_frames = params.get<uint16_t>("startup_frames", 10);
+	convergence_frames = params.get<unsigned int>("convergence_frames", 6);
 	fast_reduce_threshold =
 		params.get<double>("fast_reduce_threshold", 0.4);
 	base_ev = params.get<double>("base_ev", 1.0);
@@ -206,6 +207,16 @@ void Agc::Resume()
 	fixed_analogue_gain_ = 0;
 }
 
+unsigned int Agc::GetConvergenceFrames() const
+{
+	// If shutter and gain have been explicitly set, there is no
+	// convergence to happen, so no need to drop any frames - return zero.
+	if (fixed_shutter_ && fixed_analogue_gain_)
+		return 0;
+	else
+		return config_.convergence_frames;
+}
+
 void Agc::SetEv(double ev)
 {
 	ev_ = ev;
diff --git a/src/ipa/raspberrypi/controller/rpi/agc.hpp b/src/ipa/raspberrypi/controller/rpi/agc.hpp
index 95db1812..05c334e4 100644
--- a/src/ipa/raspberrypi/controller/rpi/agc.hpp
+++ b/src/ipa/raspberrypi/controller/rpi/agc.hpp
@@ -52,6 +52,7 @@ struct AgcConfig {
 	Pwl Y_target;
 	double speed;
 	uint16_t startup_frames;
+	unsigned int convergence_frames;
 	double max_change;
 	double min_change;
 	double fast_reduce_threshold;
@@ -74,6 +75,7 @@ public:
 	bool IsPaused() const override;
 	void Pause() override;
 	void Resume() override;
+	unsigned int GetConvergenceFrames() const override;
 	void SetEv(double ev) override;
 	void SetFlickerPeriod(double flicker_period) override;
 	void SetFixedShutter(double fixed_shutter) override; // microseconds
-- 
2.20.1