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

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.

> 
>> Suggested-by: Alex Deucher <[email protected]>
>> Cc: Bjorn Helgaas <[email protected]>
>> Cc: [email protected]
>> Signed-off-by: Vasant Hegde <[email protected]>
>> ---
>>   drivers/pci/quirks.c | 2 ++
>>   1 file changed, 2 insertions(+)
>>
>> diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
>> index b09f27f7846f..d55657347d88 100644
>> --- a/drivers/pci/quirks.c
>> +++ b/drivers/pci/quirks.c
>> @@ -5686,6 +5686,8 @@ DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x7340, quirk_amd_harvest_no_ats);
>>   DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x7341, quirk_amd_harvest_no_ats);
>>   DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x7347, quirk_amd_harvest_no_ats);
>>   DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x734f, quirk_amd_harvest_no_ats);
>> +/* Radeon Pro WX 4100 */
>> +DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x67e3, quirk_amd_harvest_no_ats);
>>   /* AMD Raven platform iGPU */
>>   DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_ATI, 0x15d8, quirk_amd_harvest_no_ats);
>>   
>> -- 
>> 2.31.1
>>