On Tue, May 23, 2023 at 09:45:49AM +0000, Moń, Tomasz wrote: > On Tue, 2023-05-23 at 12:01 +0300, Mika Westerberg wrote: > > On Tue, May 23, 2023 at 10:53:17AM +0200, Tomasz Moń wrote: > > > When I connect Thunderbolt 3 dock, two new host controllers show up: > > > * usb5 - USB 2.0 High-Speed > > > * usb6 - USB 3.0 SuperSpeed > > > > > > Devices connected through Thunderbolt 3 dock end up on expected host > > > controllers, i.e. Low/Full/High-Speed devices connect to usb5 and > > > SuperSpeed devices end up on usb6. > > > > > > Is Thunderbolt 3 essentially tunnelling the USB 2.0 traffic (by > > > tunnelling PCIe xHCI host controller traffic) on the superspeed > > > differential pairs (operating in alternate TBT3 mode)? > > > > It is not. The USB 2.x wires are separate on type-C cables. > > Yes, the USB 2.x wires are separate on type-C cables. But this does not > answer the question why there is new USB 2.0 High-Speed controller > showing up that the devices do connect to. So for the xHCI on the dock itself, I think this is what you mean, it is just a normal PCIe endpoint and all that traffic goes over a PCIe tunnel, including the USB 2.x.
