v4l2: v4l2_compat: Add V4L2 compatibility layer

Add libcamera V4L2 compatibility layer.

This initial implementation supports the minimal set of V4L2 operations,
which allows getting, setting, and enumerating formats, and streaming
frames from a video device. Some data about the wrapped V4L2 video
device are hardcoded.

Add a build option named 'v4l2' and adjust the build system to
selectively compile the V4L2 compatibility layer.

For now we match the V4L2 device node to a libcamera camera based on a
devnum that a pipeline handler may optionally map to a libcamera
camera.

Signed-off-by: Paul Elder <paul.elder@ideasonboard.com>
Reviewed-by: Jacopo Mondi <jacopo@jmondi.org>
Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

1 files changed, 644 insertions, 0 deletions

diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
new file mode 100644
index 00000000..559caba6
--- /dev/null
+++ b/src/v4l2/v4l2_camera_proxy.cpp
@@ -0,0 +1,644 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2019, Google Inc.
+ *
+ * v4l2_camera_proxy.cpp - Proxy to V4L2 compatibility camera
+ */
+
+#include "v4l2_camera_proxy.h"
+
+#include <algorithm>
+#include <errno.h>
+#include <linux/drm_fourcc.h>
+#include <linux/videodev2.h>
+#include <string.h>
+#include <sys/mman.h>
+
+#include <libcamera/camera.h>
+#include <libcamera/object.h>
+
+#include "log.h"
+#include "utils.h"
+#include "v4l2_camera.h"
+#include "v4l2_compat_manager.h"
+
+#define KERNEL_VERSION(a, b, c) (((a) << 16) + ((b) << 8) + (c))
+
+using namespace libcamera;
+
+LOG_DECLARE_CATEGORY(V4L2Compat);
+
+V4L2CameraProxy::V4L2CameraProxy(unsigned int index,
+				 std::shared_ptr<Camera> camera)
+	: refcount_(0), index_(index), bufferCount_(0), currentBuf_(0),
+	  vcam_(utils::make_unique<V4L2Camera>(camera))
+{
+	querycap(camera);
+}
+
+int V4L2CameraProxy::open(bool nonBlocking)
+{
+	LOG(V4L2Compat, Debug) << "Servicing open";
+
+	int ret;
+	vcam_->invokeMethod(&V4L2Camera::open, ConnectionTypeBlocking,
+			    &ret);
+	if (ret < 0) {
+		errno = -ret;
+		return -1;
+	}
+
+	nonBlocking_ = nonBlocking;
+
+	vcam_->invokeMethod(&V4L2Camera::getStreamConfig,
+			    ConnectionTypeBlocking, &streamConfig_);
+	setFmtFromConfig(streamConfig_);
+	sizeimage_ = calculateSizeImage(streamConfig_);
+
+	refcount_++;
+
+	return 0;
+}
+
+void V4L2CameraProxy::dup()
+{
+	refcount_++;
+}
+
+void V4L2CameraProxy::close()
+{
+	LOG(V4L2Compat, Debug) << "Servicing close";
+
+	if (--refcount_ > 0)
+		return;
+
+	vcam_->invokeMethod(&V4L2Camera::close, ConnectionTypeBlocking);
+}
+
+void *V4L2CameraProxy::mmap(size_t length, int prot, int flags, off_t offset)
+{
+	LOG(V4L2Compat, Debug) << "Servicing mmap";
+
+	/* \todo Validate prot and flags properly. */
+	if (prot != (PROT_READ | PROT_WRITE)) {
+		errno = EINVAL;
+		return MAP_FAILED;
+	}
+
+	unsigned int index = offset / sizeimage_;
+	if (index * sizeimage_ != offset || length != sizeimage_) {
+		errno = EINVAL;
+		return MAP_FAILED;
+	}
+
+	void *val;
+	vcam_->invokeMethod(&V4L2Camera::mmap, ConnectionTypeBlocking,
+			    &val, index);
+
+	buffers_[index].flags |= V4L2_BUF_FLAG_MAPPED;
+	mmaps_[val] = index;
+
+	return val;
+}
+
+int V4L2CameraProxy::munmap(void *addr, size_t length)
+{
+	LOG(V4L2Compat, Debug) << "Servicing munmap";
+
+	auto iter = mmaps_.find(addr);
+	if (iter == mmaps_.end() || length != sizeimage_) {
+		errno = EINVAL;
+		return -1;
+	}
+
+	buffers_[iter->second].flags &= ~V4L2_BUF_FLAG_MAPPED;
+	mmaps_.erase(iter);
+
+	return 0;
+}
+
+bool V4L2CameraProxy::validateBufferType(uint32_t type)
+{
+	return type == V4L2_BUF_TYPE_VIDEO_CAPTURE;
+}
+
+bool V4L2CameraProxy::validateMemoryType(uint32_t memory)
+{
+	return memory == V4L2_MEMORY_MMAP;
+}
+
+void V4L2CameraProxy::setFmtFromConfig(StreamConfiguration &streamConfig)
+{
+	curV4L2Format_.fmt.pix.width = streamConfig.size.width;
+	curV4L2Format_.fmt.pix.height = streamConfig.size.height;
+	curV4L2Format_.fmt.pix.pixelformat = drmToV4L2(streamConfig.pixelFormat);
+	curV4L2Format_.fmt.pix.field = V4L2_FIELD_NONE;
+	curV4L2Format_.fmt.pix.bytesperline =
+		bplMultiplier(curV4L2Format_.fmt.pix.pixelformat) *
+		curV4L2Format_.fmt.pix.width;
+	curV4L2Format_.fmt.pix.sizeimage =
+		imageSize(curV4L2Format_.fmt.pix.pixelformat,
+			  curV4L2Format_.fmt.pix.width,
+			  curV4L2Format_.fmt.pix.height);
+	curV4L2Format_.fmt.pix.colorspace = V4L2_COLORSPACE_SRGB;
+}
+
+unsigned int V4L2CameraProxy::calculateSizeImage(StreamConfiguration &streamConfig)
+{
+	/*
+	 * \todo Merge this method with setFmtFromConfig (need imageSize to
+	 * support all libcamera formats first, or filter out MJPEG for now).
+	 */
+	return imageSize(drmToV4L2(streamConfig.pixelFormat),
+			 streamConfig.size.width,
+			 streamConfig.size.height);
+}
+
+void V4L2CameraProxy::querycap(std::shared_ptr<Camera> camera)
+{
+	std::string driver = "libcamera";
+	std::string bus_info = driver + ":" + std::to_string(index_);
+
+	utils::strlcpy(reinterpret_cast<char *>(capabilities_.driver), driver.c_str(),
+		       sizeof(capabilities_.driver));
+	utils::strlcpy(reinterpret_cast<char *>(capabilities_.card), camera->name().c_str(),
+		       sizeof(capabilities_.card));
+	utils::strlcpy(reinterpret_cast<char *>(capabilities_.bus_info), bus_info.c_str(),
+		       sizeof(capabilities_.bus_info));
+	/* \todo Put this in a header/config somewhere. */
+	capabilities_.version = KERNEL_VERSION(5, 2, 0);
+	capabilities_.device_caps = V4L2_CAP_VIDEO_CAPTURE;
+	capabilities_.capabilities = capabilities_.device_caps
+				   | V4L2_CAP_DEVICE_CAPS;
+	memset(capabilities_.reserved, 0, sizeof(capabilities_.reserved));
+}
+
+void V4L2CameraProxy::updateBuffers()
+{
+	std::vector<FrameMetadata> completedBuffers = vcam_->completedBuffers();
+	for (FrameMetadata &fmd : completedBuffers) {
+		struct v4l2_buffer &buf = buffers_[fmd.index()];
+
+		switch (fmd.status()) {
+		case Buffer::Status::BufferSuccess:
+			buf.bytesused = fmd.bytesused();
+			buf.field = V4L2_FIELD_NONE;
+			buf.timestamp.tv_sec = fmd.timestamp() / 1000000000;
+			buf.timestamp.tv_usec = fmd.timestamp() % 1000000;
+			buf.sequence = fmd.sequence();
+
+			buf.flags |= V4L2_BUF_FLAG_DONE;
+			break;
+		case Buffer::Status::BufferError:
+			buf.flags |= V4L2_BUF_FLAG_ERROR;
+			break;
+		default:
+			break;
+		}
+	}
+}
+
+int V4L2CameraProxy::vidioc_querycap(struct v4l2_capability *arg)
+{
+	LOG(V4L2Compat, Debug) << "Servicing vidioc_querycap";
+
+	*arg = capabilities_;
+
+	return 0;
+}
+
+int V4L2CameraProxy::vidioc_enum_fmt(struct v4l2_fmtdesc *arg)
+{
+	LOG(V4L2Compat, Debug) << "Servicing vidioc_enum_fmt";
+
+	if (!validateBufferType(arg->type) ||
+	    arg->index > streamConfig_.formats().pixelformats().size())
+		return -EINVAL;
+
+	/* \todo Add map from format to description. */
+	utils::strlcpy(reinterpret_cast<char *>(arg->description), "Video Format Description",
+		       sizeof(arg->description));
+	arg->pixelformat = drmToV4L2(streamConfig_.formats().pixelformats()[arg->index]);
+
+	return 0;
+}
+
+int V4L2CameraProxy::vidioc_g_fmt(struct v4l2_format *arg)
+{
+	LOG(V4L2Compat, Debug) << "Servicing vidioc_g_fmt";
+
+	if (!validateBufferType(arg->type))
+		return -EINVAL;
+
+	memset(&arg->fmt, 0, sizeof(arg->fmt));
+	arg->fmt.pix = curV4L2Format_.fmt.pix;
+
+	return 0;
+}
+
+int V4L2CameraProxy::vidioc_s_fmt(struct v4l2_format *arg)
+{
+	LOG(V4L2Compat, Debug) << "Servicing vidioc_s_fmt";
+
+	int ret = vidioc_try_fmt(arg);
+	if (ret < 0)
+		return ret;
+
+	Size size(arg->fmt.pix.width, arg->fmt.pix.height);
+	vcam_->invokeMethod(&V4L2Camera::configure, ConnectionTypeBlocking,
+			    &ret, &streamConfig_, size,
+			    v4l2ToDrm(arg->fmt.pix.pixelformat), bufferCount_);
+	if (ret < 0)
+		return -EINVAL;
+
+	unsigned int sizeimage = calculateSizeImage(streamConfig_);
+	if (sizeimage == 0)
+		return -EINVAL;
+
+	sizeimage_ = sizeimage;
+
+	setFmtFromConfig(streamConfig_);
+
+	return 0;
+}
+
+int V4L2CameraProxy::vidioc_try_fmt(struct v4l2_format *arg)
+{
+	LOG(V4L2Compat, Debug) << "Servicing vidioc_try_fmt";
+	if (!validateBufferType(arg->type))
+		return -EINVAL;
+
+	PixelFormat format = v4l2ToDrm(arg->fmt.pix.pixelformat);
+	const std::vector<PixelFormat> &formats =
+		streamConfig_.formats().pixelformats();
+	if (std::find(formats.begin(), formats.end(), format) == formats.end())
+		format = streamConfig_.formats().pixelformats()[0];
+
+	Size size(arg->fmt.pix.width, arg->fmt.pix.height);
+	const std::vector<Size> &sizes = streamConfig_.formats().sizes(format);
+	if (std::find(sizes.begin(), sizes.end(), size) == sizes.end())
+		size = streamConfig_.formats().sizes(format)[0];
+
+	arg->fmt.pix.width        = size.width;
+	arg->fmt.pix.height       = size.height;
+	arg->fmt.pix.pixelformat  = v4l2ToDrm(format);
+	arg->fmt.pix.field        = V4L2_FIELD_NONE;
+	arg->fmt.pix.bytesperline = bplMultiplier(drmToV4L2(format)) *
+				    arg->fmt.pix.width;
+	arg->fmt.pix.sizeimage    = imageSize(drmToV4L2(format),
+					      arg->fmt.pix.width,
+					      arg->fmt.pix.height);
+	arg->fmt.pix.colorspace   = V4L2_COLORSPACE_SRGB;
+
+	return 0;
+}
+
+int V4L2CameraProxy::freeBuffers()
+{
+	LOG(V4L2Compat, Debug) << "Freeing libcamera bufs";
+
+	int ret;
+	vcam_->invokeMethod(&V4L2Camera::streamOff,
+			    ConnectionTypeBlocking, &ret);
+	if (ret < 0) {
+		LOG(V4L2Compat, Error) << "Failed to stop stream";
+		return ret;
+	}
+	vcam_->invokeMethod(&V4L2Camera::freeBuffers, ConnectionTypeBlocking);
+	bufferCount_ = 0;
+
+	return 0;
+}
+
+int V4L2CameraProxy::vidioc_reqbufs(struct v4l2_requestbuffers *arg)
+{
+	int ret;
+
+	LOG(V4L2Compat, Debug) << "Servicing vidioc_reqbufs";
+	if (!validateBufferType(arg->type) ||
+	    !validateMemoryType(arg->memory))
+		return -EINVAL;
+
+	LOG(V4L2Compat, Debug) << arg->count << " buffers requested ";
+
+	arg->capabilities = V4L2_BUF_CAP_SUPPORTS_MMAP;
+
+	if (arg->count == 0)
+		return freeBuffers();
+
+	Size size(curV4L2Format_.fmt.pix.width, curV4L2Format_.fmt.pix.height);
+	vcam_->invokeMethod(&V4L2Camera::configure, ConnectionTypeBlocking,
+			    &ret, &streamConfig_, size,
+			    v4l2ToDrm(curV4L2Format_.fmt.pix.pixelformat),
+			    arg->count);
+	if (ret < 0)
+		return -EINVAL;
+
+	sizeimage_ = calculateSizeImage(streamConfig_);
+	if (sizeimage_ == 0)
+		return -EINVAL;
+
+	setFmtFromConfig(streamConfig_);
+
+	arg->count = streamConfig_.bufferCount;
+	bufferCount_ = arg->count;
+
+	vcam_->invokeMethod(&V4L2Camera::allocBuffers,
+			    ConnectionTypeBlocking, &ret, arg->count);
+	if (ret < 0) {
+		arg->count = 0;
+		return ret;
+	}
+
+	buffers_.resize(arg->count);
+	for (unsigned int i = 0; i < arg->count; i++) {
+		struct v4l2_buffer buf = {};
+		buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
+		buf.length = curV4L2Format_.fmt.pix.sizeimage;
+		buf.memory = V4L2_MEMORY_MMAP;
+		buf.m.offset = i * curV4L2Format_.fmt.pix.sizeimage;
+		buf.index = i;
+
+		buffers_[i] = buf;
+	}
+
+	LOG(V4L2Compat, Debug) << "Allocated " << arg->count << " buffers";
+
+	return 0;
+}
+
+int V4L2CameraProxy::vidioc_querybuf(struct v4l2_buffer *arg)
+{
+	LOG(V4L2Compat, Debug) << "Servicing vidioc_querybuf";
+
+	if (!validateBufferType(arg->type) ||
+	    arg->index >= bufferCount_)
+		return -EINVAL;
+
+	updateBuffers();
+
+	*arg = buffers_[arg->index];
+
+	return 0;
+}
+
+int V4L2CameraProxy::vidioc_qbuf(struct v4l2_buffer *arg)
+{
+	LOG(V4L2Compat, Debug) << "Servicing vidioc_qbuf, index = "
+			       << arg->index;
+
+	if (!validateBufferType(arg->type) ||
+	    !validateMemoryType(arg->memory) ||
+	    arg->index >= bufferCount_)
+		return -EINVAL;
+
+	int ret;
+	vcam_->invokeMethod(&V4L2Camera::qbuf, ConnectionTypeBlocking,
+			    &ret, arg->index);
+	if (ret < 0)
+		return ret;
+
+	arg->flags |= V4L2_BUF_FLAG_QUEUED;
+	arg->flags &= ~V4L2_BUF_FLAG_DONE;
+
+	return ret;
+}
+
+int V4L2CameraProxy::vidioc_dqbuf(struct v4l2_buffer *arg)
+{
+	LOG(V4L2Compat, Debug) << "Servicing vidioc_dqbuf";
+
+	if (!validateBufferType(arg->type) ||
+	    !validateMemoryType(arg->memory))
+		return -EINVAL;
+
+	if (nonBlocking_ && !vcam_->bufferSema_.tryAcquire())
+		return -EAGAIN;
+	else
+		vcam_->bufferSema_.acquire();
+
+	updateBuffers();
+
+	struct v4l2_buffer &buf = buffers_[currentBuf_];
+
+	buf.flags &= ~V4L2_BUF_FLAG_QUEUED;
+	buf.length = sizeimage_;
+	*arg = buf;
+
+	currentBuf_ = (currentBuf_ + 1) % bufferCount_;
+
+	return 0;
+}
+
+int V4L2CameraProxy::vidioc_streamon(int *arg)
+{
+	LOG(V4L2Compat, Debug) << "Servicing vidioc_streamon";
+
+	if (!validateBufferType(*arg))
+		return -EINVAL;
+
+	int ret;
+	vcam_->invokeMethod(&V4L2Camera::streamOn,
+			    ConnectionTypeBlocking, &ret);
+
+	return ret;
+}
+
+int V4L2CameraProxy::vidioc_streamoff(int *arg)
+{
+	LOG(V4L2Compat, Debug) << "Servicing vidioc_streamoff";
+
+	if (!validateBufferType(*arg))
+		return -EINVAL;
+
+	int ret;
+	vcam_->invokeMethod(&V4L2Camera::streamOff,
+			    ConnectionTypeBlocking, &ret);
+
+	for (struct v4l2_buffer &buf : buffers_)
+		buf.flags &= ~(V4L2_BUF_FLAG_QUEUED | V4L2_BUF_FLAG_DONE);
+
+	return ret;
+}
+
+int V4L2CameraProxy::ioctl(unsigned long request, void *arg)
+{
+	int ret;
+	switch (request) {
+	case VIDIOC_QUERYCAP:
+		ret = vidioc_querycap(static_cast<struct v4l2_capability *>(arg));
+		break;
+	case VIDIOC_ENUM_FMT:
+		ret = vidioc_enum_fmt(static_cast<struct v4l2_fmtdesc *>(arg));
+		break;
+	case VIDIOC_G_FMT:
+		ret = vidioc_g_fmt(static_cast<struct v4l2_format *>(arg));
+		break;
+	case VIDIOC_S_FMT:
+		ret = vidioc_s_fmt(static_cast<struct v4l2_format *>(arg));
+		break;
+	case VIDIOC_TRY_FMT:
+		ret = vidioc_try_fmt(static_cast<struct v4l2_format *>(arg));
+		break;
+	case VIDIOC_REQBUFS:
+		ret = vidioc_reqbufs(static_cast<struct v4l2_requestbuffers *>(arg));
+		break;
+	case VIDIOC_QUERYBUF:
+		ret = vidioc_querybuf(static_cast<struct v4l2_buffer *>(arg));
+		break;
+	case VIDIOC_QBUF:
+		ret = vidioc_qbuf(static_cast<struct v4l2_buffer *>(arg));
+		break;
+	case VIDIOC_DQBUF:
+		ret = vidioc_dqbuf(static_cast<struct v4l2_buffer *>(arg));
+		break;
+	case VIDIOC_STREAMON:
+		ret = vidioc_streamon(static_cast<int *>(arg));
+		break;
+	case VIDIOC_STREAMOFF:
+		ret = vidioc_streamoff(static_cast<int *>(arg));
+		break;
+	default:
+		ret = -ENOTTY;
+		break;
+	}
+
+	if (ret < 0) {
+		errno = -ret;
+		return -1;
+	}
+
+	return ret;
+}
+
+/* \todo make libcamera export these */
+int V4L2CameraProxy::bplMultiplier(unsigned int format)
+{
+	switch (format) {
+	case V4L2_PIX_FMT_NV12:
+	case V4L2_PIX_FMT_NV21:
+	case V4L2_PIX_FMT_NV16:
+	case V4L2_PIX_FMT_NV61:
+	case V4L2_PIX_FMT_NV24:
+	case V4L2_PIX_FMT_NV42:
+		return 1;
+	case V4L2_PIX_FMT_BGR24:
+	case V4L2_PIX_FMT_RGB24:
+		return 3;
+	case V4L2_PIX_FMT_ARGB32:
+		return 4;
+	case V4L2_PIX_FMT_VYUY:
+	case V4L2_PIX_FMT_YVYU:
+	case V4L2_PIX_FMT_UYVY:
+	case V4L2_PIX_FMT_YUYV:
+		return 2;
+	default:
+		return 0;
+	};
+}
+
+int V4L2CameraProxy::imageSize(unsigned int format,
+			       unsigned int width, unsigned int height)
+{
+	switch (format) {
+	case V4L2_PIX_FMT_NV12:
+	case V4L2_PIX_FMT_NV21:
+		return width * height * 3 / 2;
+	case V4L2_PIX_FMT_NV16:
+	case V4L2_PIX_FMT_NV61:
+		return width * height * 2;
+	case V4L2_PIX_FMT_NV24:
+	case V4L2_PIX_FMT_NV42:
+		return width * height * 3;
+	case V4L2_PIX_FMT_BGR24:
+	case V4L2_PIX_FMT_RGB24:
+		return width * height * 3;
+	case V4L2_PIX_FMT_ARGB32:
+		return width * height * 4;
+	case V4L2_PIX_FMT_VYUY:
+	case V4L2_PIX_FMT_YVYU:
+	case V4L2_PIX_FMT_UYVY:
+	case V4L2_PIX_FMT_YUYV:
+		return width * height * 2;
+	default:
+		return 0;
+	};
+}
+
+unsigned int V4L2CameraProxy::v4l2ToDrm(unsigned int pixelformat)
+{
+	switch (pixelformat) {
+	/* RGB formats. */
+	case V4L2_PIX_FMT_RGB24:
+		return DRM_FORMAT_BGR888;
+	case V4L2_PIX_FMT_BGR24:
+		return DRM_FORMAT_RGB888;
+	case V4L2_PIX_FMT_ARGB32:
+		return DRM_FORMAT_BGRA8888;
+
+	/* YUV packed formats. */
+	case V4L2_PIX_FMT_YUYV:
+		return DRM_FORMAT_YUYV;
+	case V4L2_PIX_FMT_YVYU:
+		return DRM_FORMAT_YVYU;
+	case V4L2_PIX_FMT_UYVY:
+		return DRM_FORMAT_UYVY;
+	case V4L2_PIX_FMT_VYUY:
+		return DRM_FORMAT_VYUY;
+
+	/* YUY planar formats. */
+	case V4L2_PIX_FMT_NV16:
+		return DRM_FORMAT_NV16;
+	case V4L2_PIX_FMT_NV61:
+		return DRM_FORMAT_NV61;
+	case V4L2_PIX_FMT_NV12:
+		return DRM_FORMAT_NV12;
+	case V4L2_PIX_FMT_NV21:
+		return DRM_FORMAT_NV21;
+	case V4L2_PIX_FMT_NV24:
+		return DRM_FORMAT_NV24;
+	case V4L2_PIX_FMT_NV42:
+		return DRM_FORMAT_NV42;
+	default:
+		return pixelformat;
+	};
+}
+
+unsigned int V4L2CameraProxy::drmToV4L2(unsigned int pixelformat)
+{
+	switch (pixelformat) {
+	/* RGB formats. */
+	case DRM_FORMAT_BGR888:
+		return V4L2_PIX_FMT_RGB24;
+	case DRM_FORMAT_RGB888:
+		return V4L2_PIX_FMT_BGR24;
+	case DRM_FORMAT_BGRA8888:
+		return V4L2_PIX_FMT_ARGB32;
+
+	/* YUV packed formats. */
+	case DRM_FORMAT_YUYV:
+		return V4L2_PIX_FMT_YUYV;
+	case DRM_FORMAT_YVYU:
+		return V4L2_PIX_FMT_YVYU;
+	case DRM_FORMAT_UYVY:
+		return V4L2_PIX_FMT_UYVY;
+	case DRM_FORMAT_VYUY:
+		return V4L2_PIX_FMT_VYUY;
+
+	/* YUY planar formats. */
+	case DRM_FORMAT_NV16:
+		return V4L2_PIX_FMT_NV16;
+	case DRM_FORMAT_NV61:
+		return V4L2_PIX_FMT_NV61;
+	case DRM_FORMAT_NV12:
+		return V4L2_PIX_FMT_NV12;
+	case DRM_FORMAT_NV21:
+		return V4L2_PIX_FMT_NV21;
+	case DRM_FORMAT_NV24:
+		return V4L2_PIX_FMT_NV24;
+	case DRM_FORMAT_NV42:
+		return V4L2_PIX_FMT_NV42;
+	default:
+		return pixelformat;
+	}
+}