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

[Semwal, Sumit]

Hi Dave, Daniel, Rob,

On Sun, Nov 27, 2011 at 12:29 PM, Rob Clark <robdclark at gmail.com> wrote:

> On Sat, Nov 26, 2011 at 8:00 AM, Daniel Vetter <daniel at ffwll.ch> wrote:
> > On Fri, Nov 25, 2011 at 17:28, Dave Airlie <airlied at gmail.com> wrote:
> >> 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
>
> > - 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
>
> > - 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.

>
> BR,
> -R
>
BR,
Sumit.

>
> > Comments?
> >
> > Cheers, Daniel
> > --
> > Daniel Vetter
> > daniel.vetter at ffwll.ch - +41 (0) 79 364 57 48 - http://blog.ffwll.ch
> > --
> > To unsubscribe from this list: send the line "unsubscribe linux-media" in
> > the body of a message to majordomo at vger.kernel.org
> > More majordomo info at  http://vger.kernel.org/majordomo-info.html
> >
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.freedesktop.org/archives/dri-devel/attachments/20111201/2ea167ad/attachment.html>