[Bug 220904] [BUG] ucsi_acpi: USB 3.0 SuperSpeed not negotiated on USB-C hot-plug

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=220904

--- Comment #2 from Thomas Jetzinger (thomas@jetzinger.com) ---
Created attachment 309097
  --> https://bugzilla.kernel.org/attachment.cgi?id=309097&action=edit
Disabling UCSI does NOT resolve the issue

Hi Heikki,

Here are the logs from two test scenarios. Both tests confirm the issue
persists regardless of UCSI driver status.

## System Info
 - ThinkPad X1 Carbon Gen 11 (21HMCTO1WW)
 - BIOS: N3XET63W (1.38)
 - Kernel: 6.18.2-zen2-1-zen (custom build, also tested on stock 6.12)
 - Dock: ThinkPad USB-C Dock Gen2 (40AS)

## Test 1: UCSI Enabled (Normal Configuration)

**Boot with dock connected:** USB 3.0 works
 - Ethernet (17ef:a387) on Bus 002 @ 5000M
 - USB3.1 Hub (17ef:a391) on Bus 002 @ 10000M

**After disconnect + reconnect:** USB 3.0 FAILS
 - Only USB 2.0 devices enumerate (480M on Bus 003)
 - Bus 002 (20Gbps SuperSpeed) is completely empty
 - Ethernet and USB 3.0 hub missing

Key log pattern:
 usb usb1: root hub lost power or was reset
 usb usb2: root hub lost power or was reset
 usb 3-3: new high-speed USB device number 14 using xhci_hcd  ← USB 2.0 only

## Test 2: UCSI Disabled (blacklist ucsi_acpi)

**Boot with dock connected:** USB 3.0 works (same as Test 1)

**After disconnect + reconnect:** USB 3.0 STILL FAILS
 - Identical failure pattern to Test 1
 - Same "root hub lost power or was reset" messages
 - Only high-speed (USB 2.0) enumeration

## Conclusion

Disabling UCSI does NOT resolve the issue. The problem appears to be in the
USB-C/Thunderbolt physical layer negotiation, not the UCSI driver. The repeated
"root hub lost power or was reset" messages on usb1/usb2 (Thunderbolt/USB4
buses) during hot-plug suggest the xHCI controller is being reset but failing
to re-enumerate SuperSpeed devices.

Full logs attached:
 - bug-220904-test1-ucsi-enabled.txt (Test 1 with UCSI)
 - bug-220904-test2-ucsi-disabled.txt (Test 2 without UCSI)

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