ipa: rpi: black_level: Add an initialValues method

This allows the IPA to discover the correct black level values even
before any frames have been processed. This is important on the PiSP
platform where the front end black level blocks must be programmed in
advance.

Signed-off-by: David Plowman <david.plowman@raspberrypi.com>
Reviewed-by: Naushir Patuck <naush@raspberrypi.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

3 files changed, 36 insertions, 3 deletions

diff --git a/src/ipa/rpi/controller/black_level_algorithm.h b/src/ipa/rpi/controller/black_level_algorithm.h
new file mode 100644
index 00000000..c2cff2f5
--- /dev/null
+++ b/src/ipa/rpi/controller/black_level_algorithm.h
@@ -0,0 +1,23 @@
+/* SPDX-License-Identifier: BSD-2-Clause */
+/*
+ * Copyright (C) 2023, Raspberry Pi Ltd
+ *
+ * black_level_algorithm.h - black level control algorithm interface
+ */
+#pragma once
+
+#include "algorithm.h"
+
+namespace RPiController {
+
+class BlackLevelAlgorithm : public Algorithm
+{
+public:
+	BlackLevelAlgorithm(Controller *controller)
+		: Algorithm(controller) {}
+	/* A black level algorithm must provide the following: */
+	virtual void initialValues(uint16_t &blackLevelR, uint16_t &blackLevelG,
+				   uint16_t &blackLevelB) = 0;
+};
+
+} /* namespace RPiController */
diff --git a/src/ipa/rpi/controller/rpi/black_level.cpp b/src/ipa/rpi/controller/rpi/black_level.cpp
index 85baec3f..2e3db51f 100644
--- a/src/ipa/rpi/controller/rpi/black_level.cpp
+++ b/src/ipa/rpi/controller/rpi/black_level.cpp
@@ -22,7 +22,7 @@ LOG_DEFINE_CATEGORY(RPiBlackLevel)
 #define NAME "rpi.black_level"
 
 BlackLevel::BlackLevel(Controller *controller)
-	: Algorithm(controller)
+	: BlackLevelAlgorithm(controller)
 {
 }
 
@@ -45,6 +45,14 @@ int BlackLevel::read(const libcamera::YamlObject &params)
 	return 0;
 }
 
+void BlackLevel::initialValues(uint16_t &blackLevelR, uint16_t &blackLevelG,
+			       uint16_t &blackLevelB)
+{
+	blackLevelR = blackLevelR_;
+	blackLevelG = blackLevelG_;
+	blackLevelB = blackLevelB_;
+}
+
 void BlackLevel::prepare(Metadata *imageMetadata)
 {
 	/*
diff --git a/src/ipa/rpi/controller/rpi/black_level.h b/src/ipa/rpi/controller/rpi/black_level.h
index 2403f7f7..d8c41c62 100644
--- a/src/ipa/rpi/controller/rpi/black_level.h
+++ b/src/ipa/rpi/controller/rpi/black_level.h
@@ -6,19 +6,21 @@
  */
 #pragma once
 
-#include "../algorithm.h"
+#include "../black_level_algorithm.h"
 #include "../black_level_status.h"
 
 /* This is our implementation of the "black level algorithm". */
 
 namespace RPiController {
 
-class BlackLevel : public Algorithm
+class BlackLevel : public BlackLevelAlgorithm
 {
 public:
 	BlackLevel(Controller *controller);
 	char const *name() const override;
 	int read(const libcamera::YamlObject &params) override;
+	void initialValues(uint16_t &blackLevelR, uint16_t &blackLevelG,
+			   uint16_t &blackLevelB) override;
 	void prepare(Metadata *imageMetadata) override;
 
 private: