[libcamera-devel] [PATCH v3] libcamera: v4l2: Set colorspace flags

[Umang Jain]

The colorspace fields are read-only from an application point of view,
both on video devices and on subdevs, unless the
V4L2_PIX_FMT_FLAG_SET_CSC or V4L2_MBUS_FRAMEFMT_SET_CSC flags
(respectively) are set when calling the S_FMT ioctl.

Signed-off-by: Umang Jain <umang.jain at ideasonboard.com>
---
 src/libcamera/v4l2_subdevice.cpp   |  8 +++++++-
 src/libcamera/v4l2_videodevice.cpp | 14 ++++++++++++--
 2 files changed, 19 insertions(+), 3 deletions(-)

diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
index e5d20f2c..d8fd92e3 100644
--- a/src/libcamera/v4l2_subdevice.cpp
+++ b/src/libcamera/v4l2_subdevice.cpp
@@ -526,7 +526,13 @@ int V4L2Subdevice::setFormat(unsigned int pad, V4L2SubdeviceFormat *format,
 	subdevFmt.format.height = format->size.height;
 	subdevFmt.format.code = format->mbus_code;
 	subdevFmt.format.field = V4L2_FIELD_NONE;
-	fromColorSpace(format->colorSpace, subdevFmt.format);
+	if (format->colorSpace) {
+		fromColorSpace(format->colorSpace, subdevFmt.format);
+
+		/* The CSC flag is only applicable to source pads. */
+		if (entity_->pads()[pad]->flags() & MEDIA_PAD_FL_SOURCE)
+			subdevFmt.format.flags |= V4L2_MBUS_FRAMEFMT_SET_CSC;
+	}
 
 	int ret = ioctl(VIDIOC_SUBDEV_S_FMT, &subdevFmt);
 	if (ret) {
diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
index b80ee1cd..5a2d0e5b 100644
--- a/src/libcamera/v4l2_videodevice.cpp
+++ b/src/libcamera/v4l2_videodevice.cpp
@@ -953,7 +953,12 @@ int V4L2VideoDevice::trySetFormatMultiplane(V4L2DeviceFormat *format, bool set)
 	pix->pixelformat = format->fourcc;
 	pix->num_planes = format->planesCount;
 	pix->field = V4L2_FIELD_NONE;
-	fromColorSpace(format->colorSpace, *pix);
+	if (format->colorSpace) {
+		fromColorSpace(format->colorSpace, *pix);
+
+		if (caps_.isVideoCapture())
+			pix->flags |= V4L2_PIX_FMT_FLAG_SET_CSC;
+	}
 
 	ASSERT(pix->num_planes <= std::size(pix->plane_fmt));
 
@@ -1023,7 +1028,12 @@ int V4L2VideoDevice::trySetFormatSingleplane(V4L2DeviceFormat *format, bool set)
 	pix->pixelformat = format->fourcc;
 	pix->bytesperline = format->planes[0].bpl;
 	pix->field = V4L2_FIELD_NONE;
-	fromColorSpace(format->colorSpace, *pix);
+	if (format->colorSpace) {
+		fromColorSpace(format->colorSpace, *pix);
+
+		if (caps_.isVideoCapture())
+			pix->flags |= V4L2_PIX_FMT_FLAG_SET_CSC;
+	}
 
 	ret = ioctl(set ? VIDIOC_S_FMT : VIDIOC_TRY_FMT, &v4l2Format);
 	if (ret) {
-- 
2.31.1