Re: ia64 implementation of lib/iomap.c

From: Jesse Barnes <jbarnes_at_engr.sgi.com>
Date: 2004-10-27 03:49:07
On Tuesday, October 26, 2004 10:06 am, Linus Torvalds wrote:
> On Tue, 26 Oct 2004, Jesse Barnes wrote:
> > I'm pretty sure this is the case.  In fact when I last discussed this
> > with Linus he indicated that an ioread shouldn't guarantee DMA completion
> > either, which would mean we could reuse the read_relaxed stuff to
> > implement it.
>
> .. but other people disagreed with me.  I think the consensus was that DMA
> completion _should_ be honoured, but if SGI knows that their machines are
> not doing it right, and take on the responsibility for fixing drivers,
> that's _their_ problem. You only need to care about a few drivers, after
> all.
>
> In short, I think of that DMA completion issue as a SGI-private
> optimization, and _not_ a general rule.

What about the relaxed read then?  Should we have ioread_relaxed?  I thought 
we had agreed that it was easier to assume relaxed semantics for ioread and 
add a dma_sync interface.  Since PCI-X and PCI-Express have optional relaxed 
semantics that might make sense...

Thanks,
Jesse
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Received on Tue Oct 26 13:54:46 2004

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