[libcamera-devel] [PATCH v2] 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>
---
changes in v2:
- Set V4L2_MBUS_FRAMEFMT_SET_CSC flag only on source pad of
  media entity
- Set V4L2_PIX_FMT_FLAG_SET_CSC on video capture devices only
---
 src/libcamera/v4l2_subdevice.cpp   | 6 ++++--
 src/libcamera/v4l2_videodevice.cpp | 8 ++++++--
 2 files changed, 10 insertions(+), 4 deletions(-)

diff --git a/src/libcamera/v4l2_subdevice.cpp b/src/libcamera/v4l2_subdevice.cpp
index 98a3911a..8f6b327f 100644
--- a/src/libcamera/v4l2_subdevice.cpp
+++ b/src/libcamera/v4l2_subdevice.cpp
@@ -459,9 +459,11 @@ 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);
+	int ret = fromColorSpace(format->colorSpace, subdevFmt.format);
+	if (ret == 0 && (entity_->pads()[pad]->flags() & MEDIA_PAD_FL_SOURCE))
+		subdevFmt.format.flags |= V4L2_MBUS_FRAMEFMT_SET_CSC;
 
-	int ret = ioctl(VIDIOC_SUBDEV_S_FMT, &subdevFmt);
+	ret = ioctl(VIDIOC_SUBDEV_S_FMT, &subdevFmt);
 	if (ret) {
 		LOG(V4L2, Error)
 			<< "Unable to set format on pad " << pad
diff --git a/src/libcamera/v4l2_videodevice.cpp b/src/libcamera/v4l2_videodevice.cpp
index 63911339..f3651740 100644
--- a/src/libcamera/v4l2_videodevice.cpp
+++ b/src/libcamera/v4l2_videodevice.cpp
@@ -940,7 +940,9 @@ 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);
+	ret = fromColorSpace(format->colorSpace, *pix);
+	if (ret == 0 && caps_.isVideoCapture())
+		pix->flags |= V4L2_PIX_FMT_FLAG_SET_CSC;
 
 	ASSERT(pix->num_planes <= std::size(pix->plane_fmt));
 
@@ -1010,7 +1012,9 @@ 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);
+	ret = fromColorSpace(format->colorSpace, *pix);
+	if (ret == 0 && 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