[PATCH v2 03/15] media: videobuf2: Allow exporting of a struct dmabuf

Umang Jain
2023-11-09T21:04:08Z

From: Dave Stevenson <dave.stevenson@raspberrypi.org>

videobuf2 only allowed exporting a dmabuf as a file descriptor,
but there are instances where having the struct dma_buf is
useful within the kernel.

Split the current implementation into two, one step which
exports a struct dma_buf, and the second which converts that
into an fd.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.org>
Signed-off-by: Umang Jain <umang.jain@ideasonboard.com>
---
.../media/common/videobuf2/videobuf2-core.c | 36 +++++++++++++------
include/media/videobuf2-core.h | 15 ++++++++
2 files changed, 40 insertions(+), 11 deletions(-)

diff --git a/drivers/media/common/videobuf2/videobuf2-core.c b/drivers/media/common/videobuf2/videobuf2-core.c
index 27aee92f3eea..8ba85c2db375 100644
--- a/drivers/media/common/videobuf2/videobuf2-core.c
+++ b/drivers/media/common/videobuf2/videobuf2-core.c
@@ -2229,49 +2229,49 @@ static int __find_plane_by_offset(struct vb2_queue *q, unsigned long off,
return -EINVAL;
}

-int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
- unsigned int index, unsigned int plane, unsigned int flags)
+struct dma_buf *vb2_core_expbuf_dmabuf(struct vb2_queue *q, unsigned int type,
+ unsigned int index, unsigned int plane,
+ unsigned int flags)
{
struct vb2_buffer *vb = NULL;
struct vb2_plane *vb_plane;
- int ret;
struct dma_buf *dbuf;

if (q->memory != VB2_MEMORY_MMAP) {
dprintk(q, 1, "queue is not currently set up for mmap\n");
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
}

if (!q->mem_ops->get_dmabuf) {
dprintk(q, 1, "queue does not support DMA buffer exporting\n");
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
}

if (flags & ~(O_CLOEXEC | O_ACCMODE)) {
dprintk(q, 1, "queue does support only O_CLOEXEC and access mode flags\n");
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
}

if (type != q->type) {
dprintk(q, 1, "invalid buffer type\n");
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
}

if (index >= q->num_buffers) {
dprintk(q, 1, "buffer index out of range\n");
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
}

vb = q->bufs[index];

if (plane >= vb->num_planes) {
dprintk(q, 1, "buffer plane out of range\n");
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
}

if (vb2_fileio_is_active(q)) {
dprintk(q, 1, "expbuf: file io in progress\n");
- return -EBUSY;
+ return ERR_PTR(-EBUSY);
}

vb_plane = &vb->planes[plane];
@@ -2283,9 +2283,23 @@ int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
if (IS_ERR_OR_NULL(dbuf)) {
dprintk(q, 1, "failed to export buffer %d, plane %d\n",
index, plane);
- return -EINVAL;
+ return ERR_PTR(-EINVAL);
}

+ return dbuf;
+}
+EXPORT_SYMBOL_GPL(vb2_core_expbuf_dmabuf);
+
+int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
+ unsigned int index, unsigned int plane, unsigned int flags)
+{
+ struct dma_buf *dbuf;
+ int ret;
+
+ dbuf = vb2_core_expbuf_dmabuf(q, type, index, plane, flags);
+ if (IS_ERR(dbuf))
+ return PTR_ERR(dbuf);
+
ret = dma_buf_fd(dbuf, flags & ~O_ACCMODE);
if (ret < 0) {
dprintk(q, 3, "buffer %d, plane %d failed to export (%d)\n",
diff --git a/include/media/videobuf2-core.h b/include/media/videobuf2-core.h
index 4b6a9d2ea372..cba4e495f6a2 100644
--- a/include/media/videobuf2-core.h
+++ b/include/media/videobuf2-core.h
@@ -925,6 +925,21 @@ int vb2_core_streamon(struct vb2_queue *q, unsigned int type);
*/
int vb2_core_streamoff(struct vb2_queue *q, unsigned int type);

+/**
+ * vb2_core_expbuf_dmabuf() - Export a buffer as a dma_buf structure
+ * @q: videobuf2 queue
+ * @type: buffer type
+ * @index: id number of the buffer
+ * @plane: index of the plane to be exported, 0 for single plane queues
+ * @flags: flags for newly created file, currently only O_CLOEXEC is
+ * supported, refer to manual of open syscall for more details
+ *
+ * Return: Returns the dmabuf pointer
+ */
+struct dma_buf *vb2_core_expbuf_dmabuf(struct vb2_queue *q, unsigned int type,
+ unsigned int index, unsigned int plane,
+ unsigned int flags);
+
/**
* vb2_core_expbuf() - Export a buffer as a file descriptor.
* @q: pointer to &struct vb2_queue with videobuf2 queue.
--
2.41.0