Re: [PATCH 1/2] PCI: Mark Radeon Pro WX 4100 ATS as broken

On 7/23/2026 9:15 PM, Mario Limonciello wrote:
> 
> 
> On 7/23/26 10:42, Bjorn Helgaas wrote:
>> On Thu, Jul 23, 2026 at 06:15:47AM +0000, Vasant Hegde wrote:
>>> If ATS is enabled then IOMMU logs below error and GPU fails to
>>> initialize.
>>>
>>> [  103.687137] iommu ivhd0: AMD-Vi: Event logged [IOTLB_INV_TIMEOUT
>>> device=0000:c4:00.0 address=0x1080006060]
>>
>> Is this a published erratum?
>>
>> Is there enough benefit to using ATS to make it worthwhile?  It would have
>> to be a pretty substantial benefit to outweigh the end-user frustration of
>> defects like this.
>>
>> If ATS isn't going to be validated by vendors, maybe we should disable it
>> on all AMD/ATI devices?  Or maybe only the GPUs?
> 
> Isn't that a pretty big performance impact to have ATS disabled?
> 
> At least I don't think I would want a blanket policy without data supporting
> it's a good idea.

Ack. I will find this GPU internally and will run some more experiement and get
back to you.


-Vasant