> 2) Identification:
> A driver supporting DMA to userspace will set the V4L2_FLAG_DMA flag, as
> returned by QUERYCAP.
Hmm, V4L2_FLAG_DMA is a bad name. Capture to mmap()'ed kernel buffers is
DMA too...
> struct v4l2_dmabuffer *dmabuf;
> struct v4l2_dmabuffer
> {
> void *start;
> unsigned long size;
> unsigned long stride;
> unsigned long reserved[2];
> };
>
> The dmabuf pointer passed by the application is a pointer to an array of
> struct v4l2_dmabuffer, with one element for each plane in the color
> format (for the current formats, that would be one plane for the packed
> formats, and 3 for the planar formats).
>
> *start is the start address of the buffer.
> size is the size in bytes of the buffer.
> stride is the length in bytes of a line in the buffer.
Hmm, you mix up buffers + format here. "stride" is redundant with
v4l2_pix_format.bytesperline, which is a bad idea IMHO.
Why the extra struct in the first place? Why not simply put a pointer
to the userspace buffer into the struct v4l2_buffer?
Gerd
--
Get back there in front of the computer NOW. Christmas can wait.
-- Linus "the Grinch" Torvalds, 24 Dec 2000 on linux-kernel
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