[Bug 222091] New: Regression 7.1.10→7.2.x: poweroff hangs after Lenovo USB4 dock (40BF) connected during session; state persists after unplug

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=222091

            Bug ID: 222091
           Summary: Regression 7.1.10→7.2.x: poweroff hangs after Lenovo
                    USB4 dock (40BF) connected during session; state
                    persists after unplug
           Product: Drivers
           Version: 2.5
          Hardware: Intel
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: USB
          Assignee: drivers_usb@kernel-bugs.kernel.org
          Reporter: abadragan@gmail.com
        Regression: No

[Filed under Drivers/USB because there is no Thunderbolt component; this is a
drivers/thunderbolt (NHI) regression. Downstream report: see Red Hat Bugzilla,
Fedora component "kernel" -- URL to be added in a follow-up comment.]

REGRESSION: System fails to power off once a Lenovo ThinkPad USB4 Dock 5000
(40BF) has been connected during the session. Userspace shutdown completes
cleanly (journal shows poweroff.target reached, filesystems synced, journald
stopped), then the machine hangs at the firmware splash screen and requires a
hard power-off. The state is LATCHED: unplugging the dock afterwards does not
help; only sessions where the dock was never connected power off normally.

BISECTION (all verified on this machine):
  6.19.10-300.fc44  GOOD  (install-era kernel)
  6.19.12-300.fc44  GOOD
  7.1.10-200.fc44   GOOD  (also verified on a parallel Bluefin install with
                           identical kernel config and cmdline)
  7.2.5-200.fc44    BAD   (first 7.x kernel this machine booted; install
                           jumped 6.19.10 -> 7.2.5)
  7.2.7-200.fc44    BAD
  7.2.8-200.fc44    BAD

ADDITIONAL FINDING: "modprobe -r thunderbolt" while docked deadlocks
permanently (process in D state). The dock router (thunderbolt 0-3) and
retimer (0-0:3.1) disconnect, then the NHI teardown blocks:

  [<0>] nhi_pci_remove+0x53/0x60 [thunderbolt]
  [<0>] pci_device_remove+0x4a/0xb0
  [<0>] device_release_driver_internal+0x19e/0x200
  [<0>] driver_detach+0x48/0x90
  [<0>] bus_remove_driver+0x78/0x110
  [<0>] pci_unregister_driver+0x36/0xe0
  [<0>] nhi_unload+0x10/0x540 [thunderbolt]

However, blacklisting the thunderbolt module entirely does NOT fix the
poweroff hang, and neither does blacklisting ucsi_acpi -- suggesting the
latched state is below these drivers (ACPI power resources / EC interaction).
The BIOS exposes \_SB_.PC00.TBT0/TBT1 power resources and hands USB4 _OSC
control to the OS at boot; ACPI tables also show pre-existing
AE_ALREADY_EXISTS errors (\_SB.BGNV, \_SB.PC00.PTMA, ...).

HARDWARE:
  Laptop: PC Specialist FusionVI 14 (Clevo/Kapok 1558:2680), Insyde BIOS
          1.07.03dTPCS (2024-10-24), Intel Core Ultra 200V (Lunar Lake)
  TB4 controller: Intel [8086:a833], driver thunderbolt
  Dock: Lenovo ThinkPad USB4 Dock 5000 (40BF), "Lenovo Dock - USB4 Router"
        (17ef:118d), Intel retimer (8086:0d9c), dock DMC fw 1.2.04 (latest)

REPRODUCER: boot 7.2.x on this hardware, attach dock at any point, then
poweroff (or "modprobe -r thunderbolt" for the unload deadlock).

WORKAROUND: pin kernel to 7.1.10-200.fc44.

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