On 21/03/17 12:25 PM, 'joro at 8bytes.org' wrote: > On Tue, Mar 21, 2017 at 04:17:40PM +0000, Deucher, Alexander wrote: >>> -----Original Message----- >>> From: 'joro at 8bytes.org' [mailto:joro at 8bytes.org] >>> Sent: Tuesday, March 21, 2017 12:11 PM >>> To: Deucher, Alexander >>> Cc: Alex Deucher; Daniel Drake; Chris Chiu; amd-gfx at lists.freedesktop.org; >>> Nath, Arindam; iommu at 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
