Re: [RFC] Relaxed PIO read vs. DMA write ordering

From: Jesse Barnes
Date: Thu Jan 08 2004 - 12:47:03 EST


On Thu, Jan 08, 2004 at 08:23:49AM -0800, Leonid Grossman wrote:
> > I interpret this to mean:
> > Setting the RO bit in the PCI-X Command Register only enables
> > the device to choose when to set RO Attribute bit when the device
> > generates a PCI-X bus cycle.
>
> Yes, this is exactly how (at least our 10GbE) PCI-X ASICs work.
> If the RO bit is set, the device decides whether the transaction
> requires strong ordering,
> and sets RO attribute accordingly.

Excellent, a card in the wild that actually does this! :) Ok, now I'll
take of my sn2 tunnel vision glasses--we don't want another readX
variant, but it sounds like we'll need pcix_enable_relaxed() _and_
pci_sync_consistent() to support non-coherent platforms well. How does
that sound?

Thanks,
Jesse
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