[Nouveau] [PATCH v5 3/7] PCI: Drop the `is_thunderbolt` attribute from PCI core

[Lukas Wunner]

On Mon, Feb 28, 2022 at 04:13:44PM -0600, Bjorn Helgaas wrote:
> On Mon, Feb 28, 2022 at 03:33:13PM +0000, Limonciello, Mario wrote:
> > > On Fri, Feb 25, 2022 at 11:42:24AM -0600, Bjorn Helgaas wrote:
> > > > That would just leave the "PCI_VSEC_ID_INTEL_TBT implies external-
> > > facing"
> > > > assumption above.  Not having a Thunderbolt spec, I have no idea how
> > > > you deal with that.
> > > 
> > > You can download the spec here:
[...]
> > > Inside the archive there is also the DVSEC spec with name "USB4 DVSEC
> > > Version 1.0.pdf".
> > 
> > The spec has Host_Router_indication (bits 18-19) as meaning external facing.
> > I'll respin the patch 3 for using that.
> 
> Thanks, please include the spec citation when you do.  And probably
> the URL, because it's not at all obvious how the casual reader would
> get from "is_thunderbolt" to a recent add-on to the USB4 spec.

PCI_VSEC_ID_INTEL_TBT is not mentioned at all in the USB4 spec,
hence there's no connection between "is_thunderbolt" and the USB4 spec.

It's a proprietary VSEC used by Intel and the only way to recognize
pre-USB4 Thunderbolt devices that I know of.  Its ID is also
different from the DVSEC IDs given in the above-mentioned spec.

Thanks,

Lukas