[libcamera-devel] [PATCH] v4l2: V4L2CameraProxy: Add EXPBUF as one of the supported ioctl

[Vedant Paranjape]

To support DMABUF as one of the memory buffer, we need to implement
EXPBUF in the v4l2 compat layer.

This patch implements vidioc_expbuf as one of the supported ioctls.

Reference issue: https://bugs.libcamera.org/show_bug.cgi?id=89

Signed-off-by: Vedant Paranjape <vedantparanjape160201 at gmail.com>
---
 src/v4l2/v4l2_camera_proxy.cpp | 41 +++++++++++++++++++++++++++++++++-
 src/v4l2/v4l2_camera_proxy.h   |  1 +
 2 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/src/v4l2/v4l2_camera_proxy.cpp b/src/v4l2/v4l2_camera_proxy.cpp
index 3610e63cade3..03e3564bfed5 100644
--- a/src/v4l2/v4l2_camera_proxy.cpp
+++ b/src/v4l2/v4l2_camera_proxy.cpp
@@ -160,7 +160,8 @@ bool V4L2CameraProxy::validateBufferType(uint32_t type)
 
 bool V4L2CameraProxy::validateMemoryType(uint32_t memory)
 {
-	return memory == V4L2_MEMORY_MMAP;
+	return (memory == V4L2_MEMORY_MMAP) ||
+			(memory == V4L2_MEMORY_DMABUF);
 }
 
 void V4L2CameraProxy::setFmtFromConfig(const StreamConfiguration &streamConfig)
@@ -624,6 +625,40 @@ int V4L2CameraProxy::vidioc_dqbuf(V4L2CameraFile *file, struct v4l2_buffer *arg,
 	return 0;
 }
 
+int V4L2CameraProxy::vidioc_expbuf(V4L2CameraFile *file, struct v4l2_exportbuffer *arg)
+{
+	LOG(V4L2Compat, Debug) << "Servicing vidioc_expbuf fd = " << file->efd();
+	/* \todo Verify that the memory type is MMAP when adding DMABUF support */
+	if (!validateBufferType(arg->type))
+		return -EINVAL;
+
+	if (arg->index >= bufferCount_)
+		return -EINVAL;
+
+	if (arg->flags & ~(O_CLOEXEC | O_ACCMODE))
+		return -EINVAL;
+
+	LOG(V4L2Compat, Debug) << arg->index << " : index of the buffer";
+
+	if (file->priority() < maxPriority())
+		return -EBUSY;
+
+	if (!hasOwnership(file) && owner_)
+		return -EBUSY;
+
+	memset(arg->reserved, 0, sizeof(arg->reserved));
+
+	arg->fd = fcntl(buffers_[arg->index].m.fd,
+			arg->flags & O_CLOEXEC ? F_DUPFD_CLOEXEC : F_DUPFD, 0);
+	arg->fd = fcntl(arg->fd, F_SETFL, 0);
+
+	LOG(V4L2Compat, Debug) << "Exported buffer at index: " << arg->index;
+
+	acquire(file);
+
+	return 0;
+}
+
 int V4L2CameraProxy::vidioc_streamon(V4L2CameraFile *file, int *arg)
 {
 	LOG(V4L2Compat, Debug) << "Servicing vidioc_streamon fd = " << file->efd();
@@ -685,6 +720,7 @@ const std::set<unsigned long> V4L2CameraProxy::supportedIoctls_ = {
 	VIDIOC_QUERYBUF,
 	VIDIOC_QBUF,
 	VIDIOC_DQBUF,
+	VIDIOC_EXPBUF,
 	VIDIOC_STREAMON,
 	VIDIOC_STREAMOFF,
 };
@@ -755,6 +791,9 @@ int V4L2CameraProxy::ioctl(V4L2CameraFile *file, unsigned long request, void *ar
 	case VIDIOC_DQBUF:
 		ret = vidioc_dqbuf(file, static_cast<struct v4l2_buffer *>(arg), &locker);
 		break;
+	case VIDIOC_EXPBUF:
+		ret = vidioc_expbuf(file, static_cast<struct v4l2_exportbuffer *>(arg));
+		break;
 	case VIDIOC_STREAMON:
 		ret = vidioc_streamon(file, static_cast<int *>(arg));
 		break;
diff --git a/src/v4l2/v4l2_camera_proxy.h b/src/v4l2/v4l2_camera_proxy.h
index fccec241879d..81ef7788e9fe 100644
--- a/src/v4l2/v4l2_camera_proxy.h
+++ b/src/v4l2/v4l2_camera_proxy.h
@@ -58,6 +58,7 @@ private:
 	int vidioc_qbuf(V4L2CameraFile *file, struct v4l2_buffer *arg);
 	int vidioc_dqbuf(V4L2CameraFile *file, struct v4l2_buffer *arg,
 			 libcamera::MutexLocker *locker);
+	int vidioc_expbuf(V4L2CameraFile *file, struct v4l2_exportbuffer *arg);
 	int vidioc_streamon(V4L2CameraFile *file, int *arg);
 	int vidioc_streamoff(V4L2CameraFile *file, int *arg);
 
-- 
2.25.1