> -----Original Message----- > From: Samuel Sieb [mailto:samuel@xxxxxxxx] > Sent: Thursday, June 15, 2017 1:02 PM > To: Joerg Roedel; Bjorn Helgaas > Cc: linux-pci@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Daniel Drake; > Deucher, Alexander; David Woodhouse > Subject: Re: [PATCH v2] PCI: Add ATS-disable quirk for AMD Stoney GPUs > > On 06/15/2017 07:04 AM, Joerg Roedel wrote: > > Hi Bjorn, > > > > 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. > >> > >> Note that the commit in the Fixes-tag is not buggy, it > >> just uncovers the problem in the hardware by increasing > >> the ATS-flush rate. > >> > >> Fixes: b1516a14657a ('iommu/amd: Implement flush queue') > >> Signed-off-by: Joerg Roedel <jroedel@xxxxxxx> > >> --- > >> drivers/pci/quirks.c | 19 +++++++++++++++++++ > >> 1 file changed, 19 insertions(+) > > > > Any more objections on this patch? Please let me know if you want to > > have something changed. > > The other patch seems to fix this issue without disabling ATS. Isn't > that better? I talked to our validation team and ATS was validated on Stoney, so this patch is just working around something else. The other patch fixes it and is a valid optimization (it should be applied eventually), but apparently the current behavior is allowed even if it's now optimal. I'm not really an ATS expert. Alex
