Re: [openib-general] Ordering between PCI config space writes and MMIO reads?

From: Roland Dreier <rdreier_at_cisco.com>
Date: 2006-10-26 00:04:56
 > I'm not sure that can work either. The PCI-X spec is very clear, you
 > must wait for a non-posted completion if you care about order. Doing a
 > config read in the driver as a surrogate flush is not good enough in
 > the general case. Like you say, a pci bridge is free to reorder all
 > in flight non-posted operations.

No, hang on.  Nothing can reorder a dependent read to start after a
write that it depends on, can it?  So a config read of PCI_COMMAND
can't start until the completion of a config write of the same
register, right?

 - R.
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Received on Thu Oct 26 00:05:21 2006

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