On Sat, Mar 31, 2018 at 12:18:16PM +0200, Lukas Wunner wrote: > On Sat, Mar 31, 2018 at 12:58:04PM +0300, Mika Westerberg wrote: > > On Sat, Mar 31, 2018 at 11:30:17AM +0200, Lukas Wunner wrote: > > > > The whole point here is that those are *not* hotplug slots just regular > > > > downstream ports. > > > > > > Okay, understood. Is this about the NHI or XHCI? Because at least > > > on Alpine Ridge (C step), the bridge above the XHCI *is* a hotplug > > > bridge. Only the bridge above the NHI is not. > > > > Yes, exactly. I tried to clarify this mechanism a bit better in the > > other email I just sent. > > But in the e-mail you just sent, the bridge above the XHCI is not a > hotplug bridge and according to the lspci output of a MacBookPro13,3 > I have here, it *is* a hotplug bridge on Alpine Ridge (C step). They are different because on Apple systems the Thunderbolt host router (switch + xHCI + NHI) are always there and thus configured by the boot firmware initially. So there is no need for this ACPI Notify() mechanism at all, so the downstream port leading to xHCI can be marked as hotplug capable (even though not needed actually). The systems I'm refering are in "native" mode which means that they use native PCIe hotplug also for the Thunderbolt host router and thus it is up to the OS to configure everything. The reason those two ports are not marked as hotplug is that then the OS does not try to distribute all remaining resources to them which leaves more space to the extension hotplug port.
