ipa: rkisp1: awb: Load white balance gains from tuning file

For the implementation of a manual colour temperature setting, it is
necessary to read predefined colour gains per colour temperature from
the tuning file. Implement this in a backwards compatible way. If no
gains are contained in the tuning file, loading just continues as
before.

Signed-off-by: Stefan Klug <stefan.klug@ideasonboard.com>
Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/ipa/rkisp1/algorithms/awb.cpp

@@ -41,6 +41,24 @@ Awb::Awb()
 {
 }
 
+/**
+ * \copydoc libcamera::ipa::Algorithm::init
+ */
+int Awb::init([[maybe_unused]] IPAContext &context, const YamlObject &tuningData)
+{
+	Interpolator<Vector<double, 2>> gainCurve;
+	int ret = gainCurve.readYaml(tuningData["colourGains"], "ct", "gains");
+	if (ret < 0)
+		LOG(RkISP1Awb, Warning)
+			<< "Failed to parse 'colourGains' "
+			<< "parameter from tuning file; "
+			<< "manual colour temperature will not work properly";
+	else
+		colourGainCurve_ = gainCurve;
+
+	return 0;
+}
+
 /**
  * \copydoc libcamera::ipa::Algorithm::configure
  */