Re: [PATCH 3/3] dma_buf: Add documentation for the new cpu access support

[Daniel Vetter]

On Sat, Mar 3, 2012 at 01:23, Sakari Ailus <sakari.ailus@xxxxxx> wrote:
> Where it should be decided which operations are being done to the buffer
> when it is passed to user space and back to kernel space?
>
> How about spliting these operations to those done on the first time the
> buffer is passed to the user space (mapping to kernel address space, for
> example) and those required every time buffer is passed from kernel to user
> and back (cache flusing)?
>
> I'm asking since any unnecessary time-consuming operations, especially as
> heavy as mapping the buffer, should be avoidable in subsystems dealing
> with streaming video, cameras etc., i.e. non-GPU users.

I'm a bit confused about your comments because this interface
extension doesn't support userspace mmap. So userspace isn't even part
of the picture. Adding mmap support is something entirely different
imo, and I have no idea yet how we should handle cache coherency for
that.

Yours, Daniel
-- 
Daniel Vetter
daniel.vetter@xxxxxxxx - +41 (0) 79 365 57 48 - http://blog.ffwll.ch
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/