Re: [PATCH v2] PCI: Add ATS-disable quirk for AMD Stoney GPUs

[Joerg Roedel]

On Sat, Apr 08, 2017 at 09:41:07AM +0200, Lukas Wunner wrote:
> On Fri, Apr 07, 2017 at 04:32:18PM +0200, Joerg Roedel wrote:
> > From: Joerg Roedel <jroedel@xxxxxxx>
> > 
> > ATS is broken on this hardware and causes IOMMU stalls and
> > system failure. Disable ATS on these devices to make them
> > usable again with IOMMU enabled.
> 
> AMD Stoney Ridge is an x86 CPU + GPU combo and this quirk pertains
> to the GPU, right?
> 
> In that case the quirk should go to arch/x86.  Paul Menzel (+cc)
> has just complained on linux-pci@ that final fixups are taking half
> a second, and I think that could be reduced if more efforts were
> spent to move arch-specific quirks out of the catch-all in
> drivers/pci/quirks.c.

The affected hardware here might be x86-only, but ATS is not. If a
broken ATS-capable plug-in card appears, we need this in generic code
anyway.

Also has anyone profiled why the fixups take so long (and on what
hardware)? Maybe the fixup-device matching can be improved instead of
cluttering arch-code with pci-fixups.


	Joerg