[PATCH v4 3/6] ipa: rkisp1: awb: Implement ColourTemperature control

[Stefan Klug]

There are many use-cases (tuning-validation, working in static
environments) where a manual ColourTemperature control is helpful.
Implement that by interpolating and applying the white balance gains
from the tuning file according to the requested colour temperature. If
colour gains are provided on the same request, they take precedence. As
the colour temperature reported in the metadata is always based on the
measurements, we don't have to touch that.

Note that in the automatic case, the colour gains are still based on the
gray world model and the ones from the tuning file get ignored.

Signed-off-by: Stefan Klug <stefan.klug at ideasonboard.com>
---
 src/ipa/rkisp1/algorithms/awb.cpp | 22 +++++++++++++++++++++-
 1 file changed, 21 insertions(+), 1 deletion(-)

diff --git a/src/ipa/rkisp1/algorithms/awb.cpp b/src/ipa/rkisp1/algorithms/awb.cpp
index c23f749c192b..d482eda5b541 100644
--- a/src/ipa/rkisp1/algorithms/awb.cpp
+++ b/src/ipa/rkisp1/algorithms/awb.cpp
@@ -31,6 +31,10 @@ namespace ipa::rkisp1::algorithms {
 
 LOG_DEFINE_CATEGORY(RkISP1Awb)
 
+constexpr int32_t kMinColourTemperature = 2500;
+constexpr int32_t kMaxColourTemperature = 10000;
+constexpr int32_t kDefaultColourTemperature = 6500;
+
 /* Minimum mean value below which AWB can't operate. */
 constexpr double kMeanMinThreshold = 2.0;
 
@@ -42,8 +46,13 @@ Awb::Awb()
 /**
  * \copydoc libcamera::ipa::Algorithm::init
  */
-int Awb::init([[maybe_unused]] IPAContext &context, const YamlObject &tuningData)
+int Awb::init(IPAContext &context, const YamlObject &tuningData)
 {
+	auto &cmap = context.ctrlMap;
+	cmap[&controls::ColourTemperature] = ControlInfo(kMinColourTemperature,
+							 kMaxColourTemperature,
+							 kDefaultColourTemperature);
+
 	MatrixInterpolator<double, 2, 1> gains;
 	int ret = gains.readYaml(tuningData["gains"], "ct", "gains");
 	if (ret < 0)
@@ -113,6 +122,17 @@ void Awb::queueRequest(IPAContext &context,
 			<< ", blue: " << awb.gains.manual.blue;
 	}
 
+	const auto &colourTemperature = controls.get(controls::ColourTemperature);
+	if (colourTemperature && !awb.autoEnabled && gains_ && !colourGains) {
+		Matrix<double, 2, 1> gains = gains_->get(*colourTemperature);
+		awb.gains.manual.red = gains[0][0];
+		awb.gains.manual.blue = gains[1][0];
+
+		LOG(RkISP1Awb, Debug)
+			<< "Set colour gains to red: " << awb.gains.manual.red
+			<< ", blue: " << awb.gains.manual.blue;
+	}
+
 	frameContext.awb.autoEnabled = awb.autoEnabled;
 
 	if (!awb.autoEnabled) {
-- 
2.43.0