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

[Tom St Denis]

On 22/03/17 07:22 AM, 'joro at 8bytes.org' wrote:
> 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;


I tried this out but still got a lockup during init.  I tried getting a 
dmesg log but it locked up before it outputted anything more (after the 
init).

Tom