Hello, Dell Latitude 5330 with 12th Gen Intel(R) Core(TM) i7-1265U contains following PCI devices: * 8086:461e - Alder Lake-P Thunderbolt 4 USB Controller * 8086:51ed - Alder Lake PCH USB 3.2 xHCI Host Controller Thunderbolt 4 USB Controller initializes first and therefore following usb host controllers are registered: * usb1 - USB 2.0 High-Speed * usb2 - USB 3.2 Enhanced SuperSpeed * usb3 - USB 2.0 High-Speed * usb4 - USB 3.1 Enhanced SuperSpeed When I connect SuperSpeed device directly to the Dell Latitude, it ends up on usb4. Low/Full/High-Speed devices end up on usb3 as expected. 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)? When I connect Thunderbolt 4 dock, the SuperSpeed devices connected to dock ports end up on usb2 host controller. However, Low/Full/High-Speed devices do end up on usb3 (USB 3.2 xHCI) and not on usb1 (Alder Lake-P Thunderbolt 4 USB Controller). Is there any condition under which the Low/Full/High-Speed devices would end up on usb1 (USB 2.0 High-Speed host controller interface created for Thunderbolt 4 USB Controller)? Does the Alder Lake-P Thunderbolt 4 USB Controller even feature USB 2.0 interface? If not, should the (effectively dummy) usb1 host controller even be registered? Is the USB 2.0 functionality provided entirely by the Alder Lake PCH USB 3.2 xHCI Host Controller (i.e. when there is no TBT3 dock connected)? -- Tomasz Moń | Senior Firmware Engineer P +48 882 826 111 | Wrocław, Poland nordicsemi.com | devzone.nordicsemi.com
