ipa: simple: Report the ColourGains in metadata

Provide the determined colour gains back into the metadata
to add to completed requests.

Reviewed-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>
Signed-off-by: Milan Zamazal <mzamazal@redhat.com>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

src/ipa/simple/algorithms/awb.cpp

@@ -17,6 +17,8 @@
 #include "libipa/colours.h"
 #include "simple/ipa_context.h"
 
+#include "control_ids.h"
+
 namespace libcamera {
 
 LOG_DEFINE_CATEGORY(IPASoftAwb)
@@ -32,15 +34,32 @@ int Awb::configure(IPAContext &context,
 	return 0;
 }
 
+void Awb::prepare(IPAContext &context,
+		  [[maybe_unused]] const uint32_t frame,
+		  IPAFrameContext &frameContext,
+		  [[maybe_unused]] DebayerParams *params)
+{
+	auto &gains = context.activeState.awb.gains;
+	frameContext.gains.red = gains.r();
+	frameContext.gains.blue = gains.b();
+}
+
 void Awb::process(IPAContext &context,
 		  [[maybe_unused]] const uint32_t frame,
-		  [[maybe_unused]] IPAFrameContext &frameContext,
+		  IPAFrameContext &frameContext,
 		  const SwIspStats *stats,
 		  ControlList &metadata)
 {
 	const SwIspStats::Histogram &histogram = stats->yHistogram;
 	const uint8_t blackLevel = context.activeState.blc.level;
 
+	const float maxGain = 1024.0;
+	const float mdGains[] = {
+		static_cast<float>(frameContext.gains.red / maxGain),
+		static_cast<float>(frameContext.gains.blue / maxGain)
+	};
+	metadata.set(controls::ColourGains, mdGains);
+
 	/*
 	 * Black level must be subtracted to get the correct AWB ratios, they
 	 * would be off if they were computed from the whole brightness range

src/ipa/simple/algorithms/awb.h

@@ -1,6 +1,6 @@
 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 /*
- * Copyright (C) 2024, Red Hat Inc.
+ * Copyright (C) 2024-2025 Red Hat Inc.
  *
  * Auto white balance
  */
@@ -20,6 +20,10 @@ public:
 	~Awb() = default;
 
 	int configure(IPAContext &context, const IPAConfigInfo &configInfo) override;
+	void prepare(IPAContext &context,
+		     const uint32_t frame,
+		     IPAFrameContext &frameContext,
+		     DebayerParams *params) override;
 	void process(IPAContext &context,
 		     const uint32_t frame,
 		     IPAFrameContext &frameContext,

src/ipa/simple/ipa_context.h

@@ -70,6 +70,10 @@ struct IPAFrameContext : public FrameContext {
 		int32_t exposure;
 		double gain;
 	} sensor;
+	struct {
+		double red;
+		double blue;
+	} gains;
 };
 
 struct IPAContext {