From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesse Barnes Date: Tue, 26 Oct 2004 17:49:07 +0000 Subject: Re: ia64 implementation of lib/iomap.c Message-Id: <200410261049.07181.jbarnes@engr.sgi.com> List-Id: References: <16759.51459.598187.91726@napali.hpl.hp.com> In-Reply-To: <16759.51459.598187.91726@napali.hpl.hp.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org 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