Re: [PATCH v1 1/2] PCI: ATS: Add function to check ATS page aligned request status.

[Sinan Kaya]

On 2/8/2019 8:02 PM, sathyanarayanan kuppuswamy wrote:
> > This means that you should probably have some kind of version check
> > here.
>
> There is no version field in ATS v1.0 spec. Also, If I follow the 
> history log in PCI spec, I think ATS if first added at v1.2. Please 
> correct me if I am wrong.

v1.2 was incorporated into PCIe spec at that time. However, the ATS spec
is old and there could be some HW that could claim to be ATS compatible.
I know AMD GPUs declare ATS capability.

See this ECN

https://composter.com.ua/documents/ats_r1.1_26Jan09.pdf

You need to validate the version field from ATS capability header to be
1 before reading this register.

See Table 5-1:  ATS Extended Capability Header