media: videobuf2: Allow exporting of a struct dmabuf

raspberrypi inclusion
category: feature
bugzilla: 50432

--------------------------------

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: NDave Stevenson <dave.stevenson@raspberrypi.org>
Signed-off-by: NFang Yafen <yafen@iscas.ac.cn>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

drivers/media/common/videobuf2/videobuf2-core.c

@@ -2129,12 +2129,12 @@ 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)
+int vb2_core_expbuf_dmabuf(struct vb2_queue *q, unsigned int type,
+			   unsigned int index, unsigned int plane,
+			   unsigned int flags, struct dma_buf **dmabuf)
 {
 	struct vb2_buffer *vb = NULL;
 	struct vb2_plane *vb_plane;
-	int ret;
 	struct dma_buf *dbuf;
 
 	if (q->memory != VB2_MEMORY_MMAP) {
@@ -2184,6 +2184,21 @@ int vb2_core_expbuf(struct vb2_queue *q, int *fd, unsigned int type,
 		return -EINVAL;
 	}
 
+	*dmabuf = dbuf;
+	return 0;
+}
+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;
+
+	ret = vb2_core_expbuf_dmabuf(q, type, index, plane, flags, &dbuf);
+	if (ret)
+		return ret;
+
 	ret = dma_buf_fd(dbuf, flags & ~O_ACCMODE);
 	if (ret < 0) {
 		dprintk(q, 3, "buffer %d, plane %d failed to export (%d)\n",

include/media/videobuf2-core.h

@@ -901,6 +901,21 @@ 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
+ * @dmabuf:    Returns the dmabuf pointer
+ *
+ */
+int vb2_core_expbuf_dmabuf(struct vb2_queue *q, unsigned int type,
+			   unsigned int index, unsigned int plane,
+			   unsigned int flags, struct dma_buf **dmabuf);
+
 /**
  * vb2_core_expbuf() - Export a buffer as a file descriptor.
  * @q:		pointer to &struct vb2_queue with videobuf2 queue.