[libcamera-devel] [PATCH v6 5/7] libcamera: Support passing ColorSpaces to V4L2 subdevices

[David Plowman]

The ColorSpace from the StreamConfiguration is now handled
appropriately in the V4L2Subdevice.

Signed-off-by: David Plowman <david.plowman at raspberrypi.com>
---
 include/libcamera/internal/v4l2_subdevice.h |  2 ++
 src/libcamera/camera_sensor.cpp             |  1 +
 src/libcamera/v4l2_subdevice.cpp            | 35 ++++++++++++++++++++-
 3 files changed, 37 insertions(+), 1 deletion(-)

diff --git a/include/libcamera/internal/v4l2_subdevice.h b/include/libcamera/internal/v4l2_subdevice.h
index 97b89fb9..a6a0a870 100644
--- a/include/libcamera/internal/v4l2_subdevice.h
+++ b/include/libcamera/internal/v4l2_subdevice.h
@@ -14,6 +14,7 @@
 #include <libcamera/base/class.h>
 #include <libcamera/base/log.h>
 
+#include <libcamera/color_space.h>
 #include <libcamera/geometry.h>
 
 #include "libcamera/internal/formats.h"
@@ -27,6 +28,7 @@ class MediaDevice;
 struct V4L2SubdeviceFormat {
 	uint32_t mbus_code;
 	Size size;
+	std::optional<ColorSpace> colorSpace;
 
 	const std::string toString() const;
 	uint8_t bitsPerPixel() const;
diff --git a/src/libcamera/camera_sensor.cpp b/src/libcamera/camera_sensor.cpp
index 9fdb8c09..6fcd1c1d 100644
--- a/src/libcamera/camera_sensor.cpp
+++ b/src/libcamera/camera_sensor.cpp
@@ -613,6 +613,7 @@ V4L2SubdeviceFormat CameraSensor::getFormat(const std::vector<unsigned int> &mbu
 	V4L2SubdeviceFormat format{
 		.mbus_code = bestCode,
 		.size = *bestSize,
+		.colorSpace = ColorSpace::Raw,
 	};
 
 	return format;
diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
index 023e2328..b60ab69a 100644
--- a/src/libcamera/v4l2_subdevice.cpp
+++ b/src/libcamera/v4l2_subdevice.cpp
@@ -168,6 +168,16 @@ const std::map<uint32_t, V4L2SubdeviceFormatInfo> formatInfoMap = {
  * \brief The image size in pixels
  */
 
+/**
+ * \var V4L2SubdeviceFormat::colorSpace
+ * \brief The color space of the pixels
+ *
+ * The color space of the image. When setting the format this may be
+ * unset, in which case the driver gets to use its default color space.
+ * After being set, this value should contain the color space that the
+ * was actually used.
+ */
+
 /**
  * \brief Assemble and return a string describing the format
  * \return A string describing the V4L2SubdeviceFormat
@@ -400,6 +410,16 @@ int V4L2Subdevice::getFormat(unsigned int pad, V4L2SubdeviceFormat *format,
 	format->size.height = subdevFmt.format.height;
 	format->mbus_code = subdevFmt.format.code;
 
+	format->colorSpace = toColorSpace(subdevFmt.format);
+	/*
+	 * This warning can be ignored on metadata pads. These are normally
+	 * pads other than zero.
+	 * \todo find a way to detect metadata pads and ignore them
+	 */
+	if (!format->colorSpace)
+		LOG(V4L2, Warning)
+			<< "Retrieved unrecognised color space on pad " << pad;
+
 	return 0;
 }
 
@@ -418,6 +438,9 @@ int V4L2Subdevice::getFormat(unsigned int pad, V4L2SubdeviceFormat *format,
 int V4L2Subdevice::setFormat(unsigned int pad, V4L2SubdeviceFormat *format,
 			     Whence whence)
 {
+	if (!format->colorSpace)
+		LOG(V4L2, Error) << "Setting an undefined color space";
+
 	struct v4l2_subdev_format subdevFmt = {};
 	subdevFmt.which = whence == ActiveFormat ? V4L2_SUBDEV_FORMAT_ACTIVE
 			: V4L2_SUBDEV_FORMAT_TRY;
@@ -427,7 +450,13 @@ int V4L2Subdevice::setFormat(unsigned int pad, V4L2SubdeviceFormat *format,
 	subdevFmt.format.code = format->mbus_code;
 	subdevFmt.format.field = V4L2_FIELD_NONE;
 
-	int ret = ioctl(VIDIOC_SUBDEV_S_FMT, &subdevFmt);
+	int ret = fromColorSpace(format->colorSpace, subdevFmt.format);
+	if (ret < 0)
+		LOG(V4L2, Warning)
+			<< "Setting color space unrecognised by V4L2: "
+			<< ColorSpace::toString(format->colorSpace);
+
+	ret = ioctl(VIDIOC_SUBDEV_S_FMT, &subdevFmt);
 	if (ret) {
 		LOG(V4L2, Error)
 			<< "Unable to set format on pad " << pad
@@ -439,6 +468,10 @@ int V4L2Subdevice::setFormat(unsigned int pad, V4L2SubdeviceFormat *format,
 	format->size.height = subdevFmt.format.height;
 	format->mbus_code = subdevFmt.format.code;
 
+	format->colorSpace = toColorSpace(subdevFmt.format);
+	if (!format->colorSpace)
+		LOG(V4L2, Warning) << "Unrecognised color space has been set";
+
 	return 0;
 }
 
-- 
2.20.1