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

• To: Jason Gunthorpe <[email protected]>
• Subject: Re: [openib-general] Ordering between PCI config space writes and MMIO reads?
• From: Roland Dreier <[email protected]>
• Date: Wed, 25 Oct 2006 07:04:56 -0700
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• Cc: Matthew Wilcox <[email protected]>, [email protected], Jeff Garzik <[email protected]>, [email protected], [email protected], [email protected]
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• In-reply-to: <[email protected]> (Jason Gunthorpe's message of "Tue, 24 Oct 2006 16:59:35 -0600")
• References: <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]> <[email protected]>
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 > 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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---

• References:
  • Ordering between PCI config space writes and MMIO reads?
    • From: Roland Dreier <[email protected]>
  • Re: Ordering between PCI config space writes and MMIO reads?
    • From: Jeff Garzik <[email protected]>
  • Re: Ordering between PCI config space writes and MMIO reads?
    • From: Matthew Wilcox <[email protected]>
  • Re: Ordering between PCI config space writes and MMIO reads?
    • From: Roland Dreier <[email protected]>
  • Re: Ordering between PCI config space writes and MMIO reads?
    • From: Matthew Wilcox <[email protected]>
  • Re: [openib-general] Ordering between PCI config space writes and MMIO reads?
    • From: Jason Gunthorpe <[email protected]>

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