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. Joerg
