[Bug 220904] New: [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

            Bug ID: 220904
           Summary: [BUG] ucsi_acpi: USB 3.0 SuperSpeed not negotiated on
                    USB-C hot-plug
           Product: Drivers
           Version: 2.5
    Kernel Version: 6.18.2-zen2-1-zen
          Hardware: Intel
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: USB
          Assignee: drivers_usb@kernel-bugs.kernel.org
          Reporter: thomas@jetzinger.com
        Regression: No

Created attachment 309074
  --> https://bugzilla.kernel.org/attachment.cgi?id=309074&action=edit
Kernel .config for 6.18.2-zen2-1-zen (Arch Linux zen kernel)

[1.] One line summary of the problem:
USB-C dock USB 3.0 devices fail to enumerate on hot-plug (only USB 2.0 works);
works at boot and on Windows

[2.] Full description of the problem/report:
On ThinkPad X1 Carbon Gen 11 with ThinkPad USB-C Dock Gen2 (40AS), USB 3.0
devices
(including ethernet adapter) do not enumerate when hot-plugging the dock. Only
USB 2.0
devices (audio, HID) enumerate. The same dock works correctly when connected at
boot,
and hot-plug works correctly on Windows 11, indicating this is a Linux driver
issue.

Detailed analysis:
- At boot: Dock connects via Thunderbolt 4 controller (0000:00:0d.0), USB 3.0
devices
  enumerate on Bus 2 (20Gbps SuperSpeed), ethernet (r8152) works
- On hot-plug: Thunderbolt USB buses report "root hub lost power or was reset"
but
  dock falls back to internal xHCI controller (0000:00:14.0) Bus 3 at USB 2.0
speeds only

The typec subsystem shows the issue:
- At boot: dock connects as port0-partner, port0 has USB connector bindings
  (usb2-port1, usb3-port1, usb4_port1)
- On hot-plug: dock may connect as port1-partner, but port1 has NO USB
connector
  bindings in ACPI (possible BIOS deficiency)
- Even when hot-plugging to port0: SuperSpeed lanes are not negotiated, only
USB 2.0

dmesg on hot-plug shows:
  usb usb1: root hub lost power or was reset
  usb usb2: root hub lost power or was reset
  usb 3-1: new high-speed USB device  <-- Only USB 2.0 enumeration, no
SuperSpeed

The UCSI driver does not appear to trigger USB 3.0 SuperSpeed lane
renegotiation
on partner connect. No typec connector binding messages appear on hot-plug.

Tested workarounds that do NOT fix the issue:
- xHCI controller unbind/rebind (echo 0000:00:0d.0 >
/sys/bus/pci/drivers/xhci_hcd/unbind)
- UCSI driver reload (modprobe -r ucsi_acpi && modprobe ucsi_acpi)
- Using either physical USB-C port

Working workaround: Boot with dock already connected.

[3.] Keywords (i.e., modules, networking, kernel):
ucsi_acpi, typec_ucsi, typec, USB-C, Thunderbolt, hot-plug, SuperSpeed,
xhci_hcd

[4.] Kernel information
[4.1.] Kernel version (from /proc/version):
Linux version 6.18.2-zen2-1-zen (linux-zen@archlinux) (gcc (GCC) 15.2.1
20251112, GNU ld (GNU Binutils) 2.45.1) #1 ZEN SMP PREEMPT_DYNAMIC Thu, 18 Dec
2025 18:00:58 +0000

[4.2.] Kernel .config file:
[Attached separately as kernel-config.txt]

[5.] Most recent kernel version which did not have the bug:
Unknown

[6.] Output of Oops.. message (if applicable) with symbolic information:
No kernel oops. The only relevant messages are:
  usb usb1: root hub lost power or was reset
  usb usb2: root hub lost power or was reset
And then USB 2.0-only enumeration on Bus 3 instead of SuperSpeed on Bus 2.

[7.] A small shell script or example program which triggers the problem (if
possible):
# Reproduce steps:
# 1. Boot system WITHOUT dock connected
# 2. Log in to desktop
# 3. Connect ThinkPad USB-C Dock Gen2 via USB-C cable
# 4. Check USB topology:
lsusb -t
# Expected: Dock on Bus 2 with 20000M devices
# Actual: Dock on Bus 3 with 480M devices only, Bus 2 empty

# Diagnostic commands:
ls /sys/class/typec/  # Shows port0-partner or port1-partner
ls /sys/class/typec/port0/usb*  # port0 has bindings
ls /sys/class/typec/port1/usb*  # port1 has NO bindings (ACPI issue?)
ip link show | grep enp  # Ethernet interface missing on hot-plug

[8.] Environment:
Hardware: Lenovo ThinkPad X1 Carbon Gen 11 (21HMCTO1WW)
BIOS: N3XET63W (1.38) dated 2025-10-08
Dock: ThinkPad USB-C Dock Gen2 (40AS), firmware 5.05.00
OS: Arch Linux (rolling)
Desktop: Hyprland (Wayland)

USB Controllers:
- 0000:00:0d.0: Intel Thunderbolt 4 (USB 3.2, buses 1+2)
- 0000:00:14.0: Intel Alder Lake xHCI (USB 3.1, buses 3+4)

ACPI USB-C controller: USBC000:00 with two ports (device:a2=port0,
device:a3=port1)

Related bug reports:
- Red Hat Bugzilla #2248484: UCSI driver bug
- Arch Linux Forum: https://bbs.archlinux.org/viewtopic.php?id=308325

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