Re: [RFC PATCH] dma: Add barrierless dma mapping/unmapping api

[Abhijeet Dharmapurikar]

FUJITA Tomonori wrote:
> On Tue, 26 Jan 2010 15:30:10 +1100
> Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> wrote:
>
> > On Mon, 2010-01-25 at 18:35 -0800, adharmap@xxxxxxxxxxxxxx wrote:
> > > From: Abhijeet Dharmapurikar <adharmap@xxxxxxxxxxx>
 >
> > There are people nowadays putting AXI bridges and the whole ARM
> > paraphernalia of IP cores behind them on PowerPC cores for example and I
> > can see that happening with x86 as well.
> >
> > In your case, I believe your are fixing the wrong problem anyways. The
> > right approach would be instead to put all your buffer into an sglist
> > and use dma_map/unmap_sg().
>
> Agreed again. That's exactly what I suggested before:
>
> http://marc.info/?l=linux-kernel&m=126294076917753&w=2

I somehow missed your post, my apologies. Agreed that dma_map/unmap_sg 
would be the correct api to use here, however they still call the 
dmac_.*_range to map buffers. I could change those calls to do a barrier 
 only after mapping the last buffer. This would be much more cleaner 
than introducing a .*_nobarrier API.

Thanks for all the replies.

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