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

[Mika Westerberg <mika.westerberg@linux.intel.com>]

Hi,

On Mon, Feb 28, 2022 at 10:36:59PM +0000, Limonciello, Mario wrote:
> [AMD Official Use Only]
> 
> > -----Original Message-----
> > From: Lukas Wunner <lukas@wunner.de>
> > Sent: Monday, February 28, 2022 16:33
> > To: Bjorn Helgaas <helgaas@kernel.org>
> > Cc: Limonciello, Mario <Mario.Limonciello@amd.com>; Mika Westerberg
> > <mika.westerberg@linux.intel.com>; Michael Jamet
> > <michael.jamet@intel.com>; open list:PCI SUBSYSTEM <linux-
> > pci@vger.kernel.org>; open list:THUNDERBOLT DRIVER <linux-
> > usb@vger.kernel.org>; Yehezkel Bernat <YehezkelShB@gmail.com>; open
> > list:DRM DRIVERS <dri-devel@lists.freedesktop.org>; open list:X86
> > PLATFORM DRIVERS <platform-driver-x86@vger.kernel.org>; Andreas
> > Noever <andreas.noever@gmail.com>; open list:RADEON and AMDGPU
> > DRM DRIVERS <amd-gfx@lists.freedesktop.org>; open list:DRM DRIVER FOR
> > NVIDIA GEFORCE/QUADRO GPUS <nouveau@lists.freedesktop.org>; Bjorn
> > Helgaas <bhelgaas@google.com>; Deucher, Alexander
> > <Alexander.Deucher@amd.com>
> > Subject: Re: [PATCH v5 3/7] PCI: Drop the `is_thunderbolt` attribute from PCI
> > core
> > 
> > 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,
> 
> The USB4 DVSEC spec makes comments about DVSEC_ID of 0x8086 and also
> DVSEC VENDOR_ID of 0x8086.  Is that not also present on the Intel TBT3 controllers?
> 
> My interpretation of this (and Mika's comment) was that rather than
> looking at the Intel VSEC we should look at the USB4 DVSEC to detect
> the Intel TBT3 controllers.

For pre-USB4 controllers (TBT 1-3) we need to use the existing method
(or a quirk based on device ID) as they don't have the USB4 DVSEC.