On 21/03/17 12:25 PM, 'j...@8bytes.org' wrote:
On Tue, Mar 21, 2017 at 04:17:40PM +0000, Deucher, Alexander wrote:
-----Original Message-----
From: 'j...@8bytes.org' [mailto:j...@8bytes.org]
Sent: Tuesday, March 21, 2017 12:11 PM
To: Deucher, Alexander
Cc: Alex Deucher; Daniel Drake; Chris Chiu; amd-gfx@lists.freedesktop.org;
Nath, Arindam; io...@lists.linux-foundation.org; Suthikulpanit, Suravee;
Linux Upstreaming Team
Subject: Re: amd-iommu: can't boot with amdgpu, AMD-Vi: Completion-Wait
loop timed out
On Tue, Mar 21, 2017 at 04:01:53PM +0000, Deucher, Alexander wrote:
It seems to only affect Stoney systems, but not others (Carrizo,
Bristol, etc.). Maybe we could just disable it on Stoney until we
root cause it.
Completion-wait loop timeouts indicate something is seriously wrong. How
can I detect whether I am running on a 'Stoney' system?
+ John
I'm not sure if the iommu ids are different on stoney systems compared to
Carrizo/Bristol systems. The pci ids of the GPUs are different. Stoney parts
have 0x98E4 as the pci id for the GPU.
Other question, a shot into the dark, does the GPU on these systems have
ATS? Probably yes, as they are likely HSA compatible.
Stoney is a small APU. Kind of a mini Carrizo. While it may claim to support
ATS, I don't think it was ever validated on Stoney, only Carrizo/Bristol.
Okay, so maybe ATS is broken in some way on these chips. When queue
flushes happen it will also send the ATS-invalidates, and a queue flush
can cause a storm of those. This may be the issue.
I am preparing a debug-patch that disables ATS for these GPUs so someone
with such a chip can test it.
I have a stoney I can test said patch on.
Thanks,
Tom
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