Re: ia64 implementation of lib/iomap.c

Grant Grundler
2004-10-26T17:55:52Z

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