Re: ia64 implementation of lib/iomap.c

Jesse Barnes
2004-10-26T17:49:07Z

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