libcamera: debayer_cpu: Add BGR888 output support

BGR888 is RGB888 with the red and blue pixels swapped, adjust
the debayering to swap the red and blue pixels in the bayer pattern
to add support for writing formats::BGR888.

Tested-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org> # sc8280xp Lenovo x13s
Tested-by: Pavel Machek <pavel@ucw.cz>
Reviewed-by: Milan Zamazal <mzamazal@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Stefan Klug <stefan.klug@ideasonboard.com>
Signed-off-by: Kieran Bingham <kieran.bingham@ideasonboard.com>

2 files changed, 43 insertions, 8 deletions

diff --git a/src/libcamera/software_isp/debayer_cpu.cpp b/src/libcamera/software_isp/debayer_cpu.cpp
index 82163458..5b553162 100644
--- a/src/libcamera/software_isp/debayer_cpu.cpp
+++ b/src/libcamera/software_isp/debayer_cpu.cpp
@@ -281,7 +281,7 @@ int DebayerCpu::getInputConfig(PixelFormat inputFormat, DebayerInputConfig &conf
 		config.bpp = (bayerFormat.bitDepth + 7) & ~7;
 		config.patternSize.width = 2;
 		config.patternSize.height = 2;
-		config.outputFormats = std::vector<PixelFormat>({ formats::RGB888 });
+		config.outputFormats = std::vector<PixelFormat>({ formats::RGB888, formats::BGR888 });
 		return 0;
 	}
 
@@ -291,7 +291,7 @@ int DebayerCpu::getInputConfig(PixelFormat inputFormat, DebayerInputConfig &conf
 		config.bpp = 10;
 		config.patternSize.width = 4; /* 5 bytes per *4* pixels */
 		config.patternSize.height = 2;
-		config.outputFormats = std::vector<PixelFormat>({ formats::RGB888 });
+		config.outputFormats = std::vector<PixelFormat>({ formats::RGB888, formats::BGR888 });
 		return 0;
 	}
 
@@ -302,7 +302,7 @@ int DebayerCpu::getInputConfig(PixelFormat inputFormat, DebayerInputConfig &conf
 
 int DebayerCpu::getOutputConfig(PixelFormat outputFormat, DebayerOutputConfig &config)
 {
-	if (outputFormat == formats::RGB888) {
+	if (outputFormat == formats::RGB888 || outputFormat == formats::BGR888) {
 		config.bpp = 24;
 		return 0;
 	}
@@ -338,14 +338,46 @@ int DebayerCpu::setupStandardBayerOrder(BayerFormat::Order order)
 	return 0;
 }
 
-/* \todo This ignores outputFormat since there is only 1 supported outputFormat
-   for now */
-int DebayerCpu::setDebayerFunctions(PixelFormat inputFormat, [[maybe_unused]] PixelFormat outputFormat)
+int DebayerCpu::setDebayerFunctions(PixelFormat inputFormat, PixelFormat outputFormat)
 {
 	BayerFormat bayerFormat =
 		BayerFormat::fromPixelFormat(inputFormat);
 
 	xShift_ = 0;
+	swapRedBlueGains_ = false;
+
+	auto invalidFmt = []() -> int {
+		LOG(Debayer, Error) << "Unsupported input output format combination";
+		return -EINVAL;
+	};
+
+	switch (outputFormat) {
+	case formats::RGB888:
+		break;
+	case formats::BGR888:
+		/* Swap R and B in bayer order to generate BGR888 instead of RGB888 */
+		swapRedBlueGains_ = true;
+
+		switch (bayerFormat.order) {
+		case BayerFormat::BGGR:
+			bayerFormat.order = BayerFormat::RGGB;
+			break;
+		case BayerFormat::GBRG:
+			bayerFormat.order = BayerFormat::GRBG;
+			break;
+		case BayerFormat::GRBG:
+			bayerFormat.order = BayerFormat::GBRG;
+			break;
+		case BayerFormat::RGGB:
+			bayerFormat.order = BayerFormat::BGGR;
+			break;
+		default:
+			return invalidFmt();
+		}
+		break;
+	default:
+		return invalidFmt();
+	}
 
 	if ((bayerFormat.bitDepth == 8 || bayerFormat.bitDepth == 10 || bayerFormat.bitDepth == 12) &&
 	    bayerFormat.packing == BayerFormat::Packing::None &&
@@ -392,8 +424,7 @@ int DebayerCpu::setDebayerFunctions(PixelFormat inputFormat, [[maybe_unused]] Pi
 		}
 	}
 
-	LOG(Debayer, Error) << "Unsupported input output format combination";
-	return -EINVAL;
+	return invalidFmt();
 }
 
 int DebayerCpu::configure(const StreamConfiguration &inputCfg,
@@ -675,6 +706,9 @@ void DebayerCpu::process(FrameBuffer *input, FrameBuffer *output, DebayerParams
 		gammaCorrection_ = params.gamma;
 	}
 
+	if (swapRedBlueGains_)
+		std::swap(params.gainR, params.gainB);
+
 	for (unsigned int i = 0; i < kRGBLookupSize; i++) {
 		constexpr unsigned int div =
 			kRGBLookupSize * DebayerParams::kGain10 / kGammaLookupSize;
diff --git a/src/libcamera/software_isp/debayer_cpu.h b/src/libcamera/software_isp/debayer_cpu.h
index 598fe021..e7a8ba74 100644
--- a/src/libcamera/software_isp/debayer_cpu.h
+++ b/src/libcamera/software_isp/debayer_cpu.h
@@ -145,6 +145,7 @@ private:
 	unsigned int lineBufferIndex_;
 	unsigned int xShift_; /* Offset of 0/1 applied to window_.x */
 	bool enableInputMemcpy_;
+	bool swapRedBlueGains_;
 	float gammaCorrection_;
 	unsigned int measuredFrames_;
 	int64_t frameProcessTime_;