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

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Date:   Thu, 25 May 2017 23:48:14 -0700
From:   Samuel Sieb <samuel@...b.net>
To:     "Deucher, Alexander" <Alexander.Deucher@....com>,
        'Joerg Roedel' <jroedel@...e.de>
Cc:     'David Woodhouse' <dwmw2@...radead.org>,
        'Joerg Roedel' <joro@...tes.org>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        "linux-pci@...r.kernel.org" <linux-pci@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Daniel Drake <drake@...lessm.com>
Subject: Re: [PATCH v2] PCI: Add ATS-disable quirk for AMD Stoney GPUs

On 05/24/2017 05:56 AM, Deucher, Alexander wrote:
>> -----Original Message-----
>> From: Joerg Roedel [mailto:jroedel@...e.de]
>> Sent: Wednesday, May 24, 2017 4:45 AM
>> To: Deucher, Alexander
>> Cc: 'David Woodhouse'; 'Joerg Roedel'; Bjorn Helgaas; linux-
>> pci@...r.kernel.org; linux-kernel@...r.kernel.org; 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 shouldn’t 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.