lkml.org 
[lkml]   [2011]   [Dec]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
SubjectRe: [Linaro-mm-sig] [RFC v2 1/2] dma-buf: Introduce dma buffer sharing mechanism
Date
On Monday 19 December 2011, Semwal, Sumit wrote:
> I didn't see a consensus on whether dma_buf should enforce some form
> of serialization within the API - so atleast for v1 of dma-buf, I
> propose to 'not' impose a restriction, and we can tackle it (add new
> ops or enforce as design?) whenever we see the first need of it - will
> that be ok? [I am bending towards the thought that it is a problem to
> solve at a bigger platform than dma_buf.]

The problem is generally understood for streaming mappings with a
single device using it: if you have a long-running mapping, you have
to use dma_sync_*. This obviously falls apart if you have multiple
devices and no serialization between the accesses.

If you don't want serialization, that implies that we cannot have
use the dma_sync_* API on the buffer, which in turn implies that
we cannot have streaming mappings. I think that's ok, but then
you have to bring back the mmap API on the buffer if you want to
allow any driver to provide an mmap function for a shared buffer.

Arnd


\
 
 \ /
  Last update: 2011-12-20 16:43    [W:0.681 / U:0.208 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site