Re: ia64 implementation of lib/iomap.c

From: Grant Grundler <iod00d_at_hp.com>
Date: 2004-10-27 03:55:52
On Tue, Oct 26, 2004 at 09:23:24AM -0700, Jesse Barnes wrote:
> I'm pretty sure this is the case.

Me too. (Re perf sensitive devices NOT using IO Port address space)

> 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.

How can a device driver guarantee all in-flight DMA has completed
before unmapping control data?
(ie buffers allocated with pci_alloc_consistent()).

PCI ordering rules dictate MMIO read flush in-flight inbound DMA.
I'm just looking for a replacement if there is going to be
a difference in semantics between readl() and io_readl().

thanks,
grant
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Received on Tue Oct 26 14:00:27 2004

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