amd-iommu: can't boot with amdgpu, AMD-Vi: Completion-Wait loop timed out

['joro@8bytes.org']

On Tue, Mar 21, 2017 at 04:30:55PM +0000, Deucher, Alexander wrote:
> > I am preparing a debug-patch that disables ATS for these GPUs so someone
> > with such a chip can test it.
> 
> Thanks Joerg.

Here is a debug patch, using the hard hammer of disabling the use of ATS
completly in the AMD IOMMU driver. If it fixes the issue I am going to
write a more upstreamable version.

But for now, please test if this fixes the issue.

Thanks,

	Joerg

diff --git a/drivers/iommu/amd_iommu.c b/drivers/iommu/amd_iommu.c
index 98940d1..f019aa6 100644
--- a/drivers/iommu/amd_iommu.c
+++ b/drivers/iommu/amd_iommu.c
@@ -467,7 +467,7 @@ static int iommu_init_device(struct device *dev)
 		struct amd_iommu *iommu;
 
 		iommu = amd_iommu_rlookup_table[dev_data->devid];
-		dev_data->iommu_v2 = iommu->is_iommu_v2;
+		dev_data->iommu_v2 = false;
 	}
 
 	dev->archdata.iommu = dev_data;
diff --git a/drivers/iommu/amd_iommu_init.c b/drivers/iommu/amd_iommu_init.c
index 6130278..41d0e64 100644
--- a/drivers/iommu/amd_iommu_init.c
+++ b/drivers/iommu/amd_iommu_init.c
@@ -171,7 +171,7 @@ int amd_iommus_present;
 
 /* IOMMUs have a non-present cache? */
 bool amd_iommu_np_cache __read_mostly;
-bool amd_iommu_iotlb_sup __read_mostly = true;
+bool amd_iommu_iotlb_sup __read_mostly = false;
 
 u32 amd_iommu_max_pasid __read_mostly = ~0;