Re: [PATCH v2] PCI: Reset PCIe devices to stop ongoing DMA

From: Rafael J. Wysocki
Date: Wed Jul 31 2013 - 17:13:24 EST

On Wednesday, July 31, 2013 03:08:03 PM Bjorn Helgaas wrote:
> [+cc Rafael, linux-acpi]
> On Tue, Jul 30, 2013 at 6:35 PM, Takao Indoh <indou.takao@xxxxxxxxxxxxxx> wrote:
> > On x86, currently IOMMU initialization run *after* PCI enumeration, but
> > what you are talking about is that it should be changed so that x86
> > IOMMU initialization is done *before* PCI enumeration like sparc, right?
> Yes. I don't know whether or when that initialization order will ever
> be changed, but I do think we should avoid building more
> infrastructure that depends on the current order.
> Changing the order is a pretty big deal because it's a lot more than
> just the IOMMU. Basically I think we should be enumerating ACPI
> devices, including the IOMMU, before PCI devices, but there's a lot of
> legacy involved in that area. Added Rafael in case he has any
> thoughts.

Well, actually, I'm not really familiar with IOMMUs, sorry.

I do think that initializing IOMMU before PCI enumeration would be better,
however. At least if the ordering should be the same on all architectures,
which I suppose is the case, that's the one I'd choose.


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