[libcamera-devel] [PATCH v4 4/5] ipa: rpi: agc: Add AgcChannelConstraint class

[David Plowman]

A channel constraint is somewhat similar to the upper/lower bound
constraints that we use elsewhere, but these constraints apply between
multiple AGC channels. For example, it lets you say things like "don't
let the channel 1 total exposure be more than 8x that of channel 0",
and so on. By using both an upper and lower bound constraint, you
could fix one AGC channel always to be a fixed ratio of another.

Also read a vector of them (if present) when loading the tuning file.

Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
Reviewed-by: Naushir Patuck <naush at raspberrypi.com>
Reviewed-by: Jacopo Mondi <jacopo.mondi at ideasonboard.com>
---
 src/ipa/rpi/controller/rpi/agc_channel.cpp | 49 ++++++++++++++++++++++
 src/ipa/rpi/controller/rpi/agc_channel.h   | 10 +++++
 2 files changed, 59 insertions(+)

diff --git a/src/ipa/rpi/controller/rpi/agc_channel.cpp b/src/ipa/rpi/controller/rpi/agc_channel.cpp
index 9c8d1a6f..afa06686 100644
--- a/src/ipa/rpi/controller/rpi/agc_channel.cpp
+++ b/src/ipa/rpi/controller/rpi/agc_channel.cpp
@@ -170,6 +170,49 @@ readConstraintModes(std::map<std::string, AgcConstraintMode> &constraintModes,
 	return { 0, first };
 }
 
+int AgcChannelConstraint::read(const libcamera::YamlObject &params)
+{
+	auto channelValue = params["channel"].get<unsigned int>();
+	if (!channelValue) {
+		LOG(RPiAgc, Error) << "AGC channel constraint must have a channel";
+		return -EINVAL;
+	}
+	channel = *channelValue;
+
+	std::string boundString = params["bound"].get<std::string>("");
+	transform(boundString.begin(), boundString.end(),
+		  boundString.begin(), ::toupper);
+	if (boundString != "UPPER" && boundString != "LOWER") {
+		LOG(RPiAgc, Error) << "AGC channel constraint type should be UPPER or LOWER";
+		return -EINVAL;
+	}
+	bound = boundString == "UPPER" ? Bound::UPPER : Bound::LOWER;
+
+	auto factorValue = params["factor"].get<double>();
+	if (!factorValue) {
+		LOG(RPiAgc, Error) << "AGC channel constraint must have a factor";
+		return -EINVAL;
+	}
+	factor = *factorValue;
+
+	return 0;
+}
+
+static int readChannelConstraints(std::vector<AgcChannelConstraint> &channelConstraints,
+				  const libcamera::YamlObject &params)
+{
+	for (const auto &p : params.asList()) {
+		AgcChannelConstraint constraint;
+		int ret = constraint.read(p);
+		if (ret)
+			return ret;
+
+		channelConstraints.push_back(constraint);
+	}
+
+	return 0;
+}
+
 int AgcConfig::read(const libcamera::YamlObject &params)
 {
 	LOG(RPiAgc, Debug) << "AgcConfig";
@@ -188,6 +231,12 @@ int AgcConfig::read(const libcamera::YamlObject &params)
 	if (ret)
 		return ret;
 
+	if (params.contains("channel_constraints")) {
+		ret = readChannelConstraints(channelConstraints, params["channel_constraints"]);
+		if (ret)
+			return ret;
+	}
+
 	ret = yTarget.read(params["y_target"]);
 	if (ret)
 		return ret;
diff --git a/src/ipa/rpi/controller/rpi/agc_channel.h b/src/ipa/rpi/controller/rpi/agc_channel.h
index b2f554db..ceaab12f 100644
--- a/src/ipa/rpi/controller/rpi/agc_channel.h
+++ b/src/ipa/rpi/controller/rpi/agc_channel.h
@@ -44,11 +44,21 @@ struct AgcConstraint {
 
 typedef std::vector<AgcConstraint> AgcConstraintMode;
 
+struct AgcChannelConstraint {
+	enum class Bound { LOWER = 0,
+			   UPPER = 1 };
+	Bound bound;
+	unsigned int channel;
+	double factor;
+	int read(const libcamera::YamlObject &params);
+};
+
 struct AgcConfig {
 	int read(const libcamera::YamlObject &params);
 	std::map<std::string, AgcMeteringMode> meteringModes;
 	std::map<std::string, AgcExposureMode> exposureModes;
 	std::map<std::string, AgcConstraintMode> constraintModes;
+	std::vector<AgcChannelConstraint> channelConstraints;
 	Pwl yTarget;
 	double speed;
 	uint16_t startupFrames;
-- 
2.30.2