[Linaro-mm-sig] [RFC 1/2] dma-buf: Introduce dma buffer sharing mechanism

Hi Dave, Daniel, Rob,

On Sun, Nov 27, 2011 at 12:29 PM, Rob Clark [off-list ref] wrote:

quoted

On Sat, Nov 26, 2011 at 8:00 AM, Daniel Vetter [off-list ref] wrote:

quoted

On Fri, Nov 25, 2011 at 17:28, Dave Airlie [off-list ref] wrote:

quoted

I've rebuilt my PRIME interface on top of dmabuf to see how it would
work,

I've got primed gears running again on top, but I expect all my object
lifetime and memory ownership rules need fixing up (i.e. leaks like a
sieve).

http://cgit.freedesktop.org/~airlied/linux/log/?h=drm-prime-dmabuf

has the i915/nouveau patches for the kernel to produce the prime
interface.

I've noticed that your implementations for get_scatterlist (at least
for the i915 driver) doesn't return the sg table mapped into the
device address space. I've checked and the documentation makes it
clear that this should be the case (and we really need this to support
certain insane hw), but the get/put_scatterlist names are a bit
misleading. Proposal:

- use struct sg_table instead of scatterlist like you've already done
in you branch. Simply more consistent with the dma api.

yup

quoted

- rename get/put_scatterlist into map/unmap for consistency with all
the map/unmap dma api functions. The attachement would then serve as
the abstract cookie to the backing storage, similar to how struct page
* works as an abstract cookie for dma_map/unmap_page. The only special
thing is that struct device * parameter because that's already part of
the attachment.

yup

quoted

- add new wrapper functions dma_buf_map_attachment and
dma_buf_unmap_attachement to hide all the pointer/vtable-chasing that
we currently expose to users of this interface.

I thought that was one of the earlier comments on the initial dmabuf
patch, but either way: yup

Thanks for your comments; I will incorporate all of these in the next
version I'll send out.

quoted

BR,
-R

BR,
Sumit.

quoted

quoted

Comments?

Cheers, Daniel
--
Daniel Vetter
daniel.vetter at ffwll.ch - +41 (0) 79 364 57 48 - http://blog.ffwll.ch
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