[libcamera-devel] [PATCH v2 3/9] libcamera: bayer_format: Add support for mbus codes

[Jacopo Mondi]

The existing implementation of the BayerFormat class supports
converting a V4L2PixelFormat to a BayerFormat and vice-versa.

Expand the class by adding support for converting a media bus code
to a BayerFormat instance, by providing a conversion table and a
dedicated constructor.

Expand the number of supported compression and expand the documentation.

Do not provide support for converting a BayerFormat to a media bus code
as the feature is currently not required.

Signed-off-by: Jacopo Mondi <jacopo at jmondi.org>
---
 include/libcamera/internal/bayer_format.h |  3 ++
 src/libcamera/bayer_format.cpp            | 66 ++++++++++++++++++++++-
 2 files changed, 68 insertions(+), 1 deletion(-)

diff --git a/include/libcamera/internal/bayer_format.h b/include/libcamera/internal/bayer_format.h
index 4280b76b016f..7d7539e275ff 100644
--- a/include/libcamera/internal/bayer_format.h
+++ b/include/libcamera/internal/bayer_format.h
@@ -30,6 +30,8 @@ public:
 		None = 0,
 		CSI2Packed = 1,
 		IPU3Packed = 2,
+		ALAW8Compression = 3,
+		DPCM8Compression = 4,
 	};
 
 	constexpr BayerFormat()
@@ -43,6 +45,7 @@ public:
 	}
 
 	explicit BayerFormat(V4L2PixelFormat v4l2Format);
+	explicit BayerFormat(unsigned int mbusCode);
 	bool isValid() const { return bitDepth != 0; }
 
 	std::string toString() const;
diff --git a/src/libcamera/bayer_format.cpp b/src/libcamera/bayer_format.cpp
index c42792ff1948..a4eba4592bfe 100644
--- a/src/libcamera/bayer_format.cpp
+++ b/src/libcamera/bayer_format.cpp
@@ -8,6 +8,9 @@
 #include "libcamera/internal/bayer_format.h"
 
 #include <map>
+#include <unordered_map>
+
+#include <linux/media-bus-format.h>
 
 #include <libcamera/transform.h>
 
@@ -45,7 +48,8 @@ namespace libcamera {
 
 /**
  * \enum BayerFormat::Packing
- * \brief Different types of packing that can be applied to a BayerFormat
+ * \brief Different types of packing or compressions that can be applied to a
+ * BayerFormat
  *
  * \var BayerFormat::None
  * \brief No packing
@@ -53,6 +57,10 @@ namespace libcamera {
  * \brief Format uses MIPI CSI-2 style packing
  * \var BayerFormat::IPU3Packed
  * \brief Format uses IPU3 style packing
+ * \var BayerFormat::ALAW8Compression
+ * \brief Format uses ALAW8 compression
+ * \var BayerFormat::DPCM8Compression
+ * \brief Format uses DPCM8 compression
  */
 
 namespace {
@@ -140,6 +148,41 @@ const std::map<BayerFormat, V4L2PixelFormat, BayerFormatComparator> bayerToV4l2{
 	{ { BayerFormat::RGGB, 16, BayerFormat::None }, V4L2PixelFormat(V4L2_PIX_FMT_SRGGB16) },
 };
 
+const std::unordered_map<unsigned int, BayerFormat> mbusCodeToBayer{
+	{ MEDIA_BUS_FMT_SBGGR8_1X8, { BayerFormat::BGGR, 8, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SGBRG8_1X8, { BayerFormat::GBRG, 8, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SGRBG8_1X8, { BayerFormat::GRBG, 8, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SRGGB8_1X8, { BayerFormat::RGGB, 8, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SBGGR10_ALAW8_1X8, { BayerFormat::BGGR, 8, BayerFormat::ALAW8Compression } },
+	{ MEDIA_BUS_FMT_SGBRG10_ALAW8_1X8, { BayerFormat::GBRG, 8, BayerFormat::ALAW8Compression } },
+	{ MEDIA_BUS_FMT_SGRBG10_ALAW8_1X8, { BayerFormat::GRBG, 8, BayerFormat::ALAW8Compression } },
+	{ MEDIA_BUS_FMT_SRGGB10_ALAW8_1X8, { BayerFormat::RGGB, 8, BayerFormat::ALAW8Compression } },
+	{ MEDIA_BUS_FMT_SBGGR10_DPCM8_1X8, { BayerFormat::BGGR, 8, BayerFormat::DPCM8Compression } },
+	{ MEDIA_BUS_FMT_SGBRG10_DPCM8_1X8, { BayerFormat::GBRG, 8, BayerFormat::DPCM8Compression } },
+	{ MEDIA_BUS_FMT_SGRBG10_DPCM8_1X8, { BayerFormat::GRBG, 8, BayerFormat::DPCM8Compression } },
+	{ MEDIA_BUS_FMT_SRGGB10_DPCM8_1X8, { BayerFormat::RGGB, 8, BayerFormat::DPCM8Compression } },
+	{ MEDIA_BUS_FMT_SBGGR10_2X8_PADHI_BE, { BayerFormat::BGGR, 10, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SBGGR10_2X8_PADHI_LE, { BayerFormat::BGGR, 10, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SBGGR10_2X8_PADLO_BE, { BayerFormat::BGGR, 10, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SBGGR10_2X8_PADLO_LE, { BayerFormat::BGGR, 10, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SBGGR10_1X10, { BayerFormat::BGGR, 10, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SGBRG10_1X10, { BayerFormat::GBRG, 10, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SGRBG10_1X10, { BayerFormat::GRBG, 10, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SRGGB10_1X10, { BayerFormat::RGGB, 10, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SBGGR12_1X12, { BayerFormat::BGGR, 12, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SGBRG12_1X12, { BayerFormat::GBRG, 12, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SGRBG12_1X12, { BayerFormat::GRBG, 12, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SRGGB12_1X12, { BayerFormat::RGGB, 12, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SBGGR14_1X14, { BayerFormat::BGGR, 14, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SGBRG14_1X14, { BayerFormat::GBRG, 14, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SGRBG14_1X14, { BayerFormat::GRBG, 14, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SRGGB14_1X14, { BayerFormat::RGGB, 14, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SBGGR16_1X16, { BayerFormat::BGGR, 16, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SGBRG16_1X16, { BayerFormat::GBRG, 16, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SGRBG16_1X16, { BayerFormat::GRBG, 16, BayerFormat::None } },
+	{ MEDIA_BUS_FMT_SRGGB16_1X16, { BayerFormat::RGGB, 16, BayerFormat::None } },
+};
+
 } /* namespace */
 
 /**
@@ -169,6 +212,22 @@ BayerFormat::BayerFormat(V4L2PixelFormat v4l2Format)
 		*this = it->second;
 }
 
+/**
+ * \brief Construct a BayerFormat from a media bus code
+ * \param[in] mbusCode The media bus code to convert into a BayerFormat
+ *
+ * The media bus code numeric identifiers are defined by the V4L2 specification.
+ */
+BayerFormat::BayerFormat(unsigned int mbusCode)
+	: order(BGGR), packing(None)
+{
+	const auto it = mbusCodeToBayer.find(mbusCode);
+	if (it == mbusCodeToBayer.end())
+		bitDepth = 0;
+	else
+		*this = it->second;
+}
+
 /**
  * \fn BayerFormat::isValid()
  * \brief Return whether a BayerFormat is valid
@@ -258,6 +317,11 @@ BayerFormat BayerFormat::transform(Transform t) const
 /**
  * \var BayerFormat::bitDepth
  * \brief The bit depth of the samples in the Bayer pattern
+ *
+ * For formats using compression schemes such as Packing::ALAW8Compression or
+ * Packing::DPCM8Compression, the bitDepth value refers to the size of the
+ * sample when transmitted on the wire or stored into memory. The resulting
+ * images need to be de-compressed to be viewed properly.
  */
 
 /**
-- 
2.29.2