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

[Samuel Sieb]

On 05/24/2017 05:56 AM, Deucher, Alexander wrote:
> > -----Original Message-----
> > From: Joerg Roedel [mailto:jroedel@xxxxxxx]
> > Sent: Wednesday, May 24, 2017 4:45 AM
> > To: Deucher, Alexander
> > Cc: 'David Woodhouse'; 'Joerg Roedel'; Bjorn Helgaas; linux-
> > pci@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Daniel Drake; Samuel
> > Sieb
> > Subject: Re: [PATCH v2] PCI: Add ATS-disable quirk for AMD Stoney GPUs
> >
> > Hi Alexander,
> >
> > On Tue, May 23, 2017 at 07:54:12PM +0000, Deucher, Alexander wrote:
> > > I finally got an answer from the hw team and we validated ATS on
> > > stoney as well so in theory this patch shouldnât actually be needed.
> > > I think we may actually be papering over some other issue.  The
> > > following patch seems to also fix this issue (and other issues):
> > > https://www.spinics.net/lists/stable/msg172631.html
> >
> > Yeah, but it still looks to me like that the hardware got into some
> > weird state with the storm of ATS invalidations sent to it.
> >
> > The Completion-Wait loop timeouts seen in the original bug report
> > indicate that the IOMMU is waiting for a response that never comes. And
> > this is probably the ATS flush completion response from the GPU, as
> > disabling ATS on the GPU makes the issue disappear.
>
> Yeah, it's weird.  My ack on the patch still stands.  Just adding some additional data.

I just tested this patch without the previous ATS disabling patch (I 
verified that ATS was enabled).  Doing a stress-test kernel build while 
running a 3D graphical application caused no disk corruption.  That was 
running for several hours.  If it's not the solution, it sure hides the 
problem really well.