On Wed, Oct 09, 2024 at 01:47:52PM +0200, Lukas Wunner wrote:
> On Wed, Oct 09, 2024 at 07:44:42AM +0300, mika.westerberg@xxxxxxxxxxxxxxx wrote:
> > On Tue, Oct 08, 2024 at 08:23:43PM +0200, Lukas Wunner wrote:
> > > Okay this seems to have been introduced by 0fc70886569c ("thunderbolt:
> > > Reset USB4 v2 host router").
> >
> > Correct, and there is similar commit for USB4 v1 routers.
> >
> > > Is that a good idea though? What if the machine was booted from a
> > > Thunderbolt-attached drive? At least on Macs that has been supported
> > > since day 1. I'd assume that it may cause issues if the connection to
> > > the drive on which the root partition resides is forcefully torn down
> > > and re-established?
> >
> > For Macs we still "discover" the topology. This is only for software
> > connection manager USB4 hosts. This same "strategy" is being used in
> > Windows nowadays, it allows to re-configure sub-optimal setup that the
> > BIOS CM might have done and avoids some issues too on AMD.
>
> Hm, I'd assume recent Apple Silicon host routers are USB4 compliant,
> so we may have to exempt those from the reset once Thunderbolt is
> brought up on them...
Sure if this is really needed. For Apple their boot firmware provides
extra information about the configured paths so it is easier for OS side
to validate. There is no such thing in the BIOS <-> OS handoff.
