Re: Possible problem with thunderbolt 4

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

On Fri, Dec 30, 2022 at 01:08:36PM +0100, Christian Schaubschläger wrote:
> 
> > No but this is not the "final" solution - just an experiment.
> >
> > Okay so we have this:
> >
> > - When both Linux and Windows uses the same firmware connection manager
> >   all work.
> >
> > - If you install Windows 11 (or whatever the fresh one is that actually
> >   supports USB4 and software connection manager) you end up in the
> >   exact same situation.
> I'm running Win10 22H2 on this machine... I could upgrade to Win11 if this helps.

Most likely it will just make the Windows work like Linux (so PXE does
not work) therere I don't suggest doing that.

> > Can you try following:
> >
> > 1. Go back to CONFIG_USB4=m
> > 2. Boot the system up
> > 3. Check that the PCIe tunneling is up and things work as expected
> > 4. Unplug the dock
> > 5. Unload the Thunderbolt driver
> >
> >   # rmmod thunderbolt
> >
> > 6. Plug the dock back
> > 7. Soft reboot the system
> >
> > Does this make the PXE boot see the connected device?
> After these steps the firmware sees the connected device!

OK.

> If I just remove the module without un- and re-plugging the cable, the
> connection is not there in the firmware after the reboot.

Right because the driver leaves all the tunnels up so the boot firmware
then finds the PCIe tunnels established.

One more experiment if you will.

Same steps 1-3 as above but then do this:

4. Disconnect the PCIe tunnel directly:

  # echo 0 > /sys/bus/thunderbolt/devices/DEVICE/authorized

(where DEVICE is typically 0-1 or 0-3 in Intel platforms)

5. Check in lspci that it is not visible anymore
6. Soft boot the system.

In other words this leaves the USB4 link and other tunnels up but not
PCIe.