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

[Joerg Roedel]

Hi Bjorn,

On Thu, Jun 15, 2017 at 02:15:45PM -0500, Bjorn Helgaas wrote:
> It was marked "superseded" in patchwork and thus off my radar.  I
> don't remember if I did that or why.  I changed it back to "New" so I
> won't forget about it.

Great!

> You mention (May 24) the original bug report.  Can you include the URL
> for that?

I think there were multiple reports, here is one I could still find:

	https://lists.linuxfoundation.org/pipermail/iommu/2017-March/020836.html

> I admit I just don't have warm fuzzies that the problem is well
> understood.

The current understanding (without my ability to debug the hardware
involved) is that the GPU in the Stoney systems gets into a weird state
when ATS invalidations are sent too fast and stops responding to the
iommu.

The iommu then can't complete the invalidation commands and the driver
throws completion-wait loop timeout messages out.



	Joerg