On Fri, Mar 17, 2017 at 11:53:09AM -0400, Alex Deucher wrote: > On Fri, Mar 17, 2017 at 8:15 AM, Daniel Drake <drake at endlessm.com> wrote: > > Hi, > > > > On Mon, Mar 13, 2017 at 2:01 PM, Deucher, Alexander > > <Alexander.Deucher at amd.com> wrote: > >> > We are unable to boot Acer Aspire E5-553G (AMD FX-9800P RADEON R7) nor > >> > Acer Aspire E5-523 with standard configurations because during boot > >> > the screen is flooded with the following error message over and over: > >> > > >> > AMD-Vi: Completion-Wait loop timed out > >> > >> We ran into similar issues and bisected it to commit b1516a14657acf81a587e9a6e733a881625eee53. I'm not too familiar with the IOMMU hardware to know if this is an iommu or display driver issue yet. > > > > We can confirm that reverting this commit solves the issue. > > > > Given that that commit is an optimization, but it has introduced a > > regression on multiple platforms, and has been like this for 8 months, > > it would be common practice to now revert this patch upstream until > > the regression is fixed. Could you please send a new patch to do this? > > > > Also, we would be happy to test any real solutions to this issue while > > we still have the affected units in hand. > > No objections to a revert here. Big objection here. Since this only happens with amdgpu so far we shouldn't rule out a display-driver issue. Reverting that patch basically destroys iommu-performance on AMD systems. Doing this for all devices just to make amdgpu working is overkill at this stage of the debugging. Joerg
