When TBT dock is plugged into ICL TBT xHCI, port without device is in CAS state, causes many warm reset fail

lspci -vvnn

firmwares are all up-to-date.

usb1 and usb2 is root hub of "00:0d.0 USB controller [0c03]: Intel Corporation Ice Lake Thunderbolt 3 USB Controller [8086:8a13] (rev 03) (prog-if 30 [XHCI])".

Mika, Matthias,

Can you please take a look at the dmesg? If it's a known bug in ICL TBT firmware/hardware, we can close this issue.

I don't know much about xHCI so Mathias can comment on that. I do remember seeing messages like:

  usb usb2-port1: Cannot enable. Maybe the USB cable is bad?

in the past but not sure if it is only with ICL. It is also weird that the TCSS xHCI is doing anything if you plug TBT 3 device since USB is not tunneled. Might be something related to Type-C or PD.

I'm not aware of any known issue like this.
Is there any USB3 device connected at all?

The only sign of a connected device is that one time CAS bit is set.

device never reaches enables state (no successful link training), no error,
not going to invalid or compliance state either.
Just stays in disabled/Disconnected, as if no device is connected.

Driver tries everything to enable the device, several resets, warm reset, turns port power
off/on, but no reaction.

(CAS -Cold Attach Status is set when xHC can't advance the link to the enabled U0 state due
to itself being in D3, or because its clocks are not running.)

> Is there any USB3 device connected at all?
No. Only a Thunderbolt Dock is connected.

> Just stays in disabled/Disconnected, as if no device is connected.
Because there's no device connected to it. Actually it seems to be completely unused.

I wonder if we can disable the Bus 01/02 xHC completely, since all internal USBs are connected to the other xHC:
$ lsusb -t
/: Bus 04.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/6p, 10000M
/: Bus 03.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/12p, 480M
    |__ Port 5: Dev 2, If 0, Class=Vendor Specific Class, Driver=, 12M
    |__ Port 9: Dev 3, If 0, Class=Video, Driver=uvcvideo, 480M
    |__ Port 9: Dev 3, If 1, Class=Video, Driver=uvcvideo, 480M
    |__ Port 9: Dev 3, If 2, Class=Video, Driver=uvcvideo, 480M
    |__ Port 9: Dev 3, If 3, Class=Video, Driver=uvcvideo, 480M
    |__ Port 9: Dev 3, If 4, Class=Application Specific Interface, Driver=, 480M
    |__ Port 10: Dev 4, If 0, Class=Wireless, Driver=btusb, 12M
    |__ Port 10: Dev 4, If 1, Class=Wireless, Driver=btusb, 12M
/: Bus 02.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/4p, 10000M
/: Bus 01.Port 1: Dev 1, Class=root_hub, Driver=xhci_hcd/1p, 480M

External USBs and Thunderbolt are also connected to Bus 03/04.

Since it doesn't seem to affect any real functionality, let's close it.