Source: linux
Version: 6.12.94-1
Severity: important
X-Debbugs-Cc: [email protected]
Dear Maintainer,
Thunderbolt 4 dock stops working completely after upgrading from
6.12.90+deb13.1-amd64 to 6.12.94+deb13-amd64. The dock is detected
and authorized by bolt but all tunnel creation fails, making peripherals
and laptop charging unavailable. A similar issue has occurred on
previous kernel upgrades on this machine.
== Hardware ==
Machine: Lenovo ThinkPad T16 Gen 4 (21QN001MSC)
CPU: AMD Ryzen AI 7 PRO 350 w/ Radeon 860M
TB controller: Intel Thunderbolt 4 Goshen Ridge [8086:0b26] rev 03
(PCI 61:00.0 / 62:00.0-04.0)
Dock: Lenovo ThinkPad Thunderbolt 4 Smart Dock Gen 2 7500
(vendor=0x108 device=0x2350)
== Regression range ==
Last working kernel: 6.12.90+deb13.1-amd64
First broken kernel: 6.12.94+deb13-amd64
== Symptoms ==
- Dock LED blinks white/orange
- Laptop does not charge via dock
- No peripherals (USB, display) detected
- bolt correctly authorizes the device (policy: iommu)
- Dock reconnect loop: detected -> tunnel failure -> disconnected -> repeat
== dmesg output (6.12.94, dock plugged in) ==
[ 261.001240] thunderbolt 1-2: new device found, vendor=0x108 device=0x2350
[ 261.001253] thunderbolt 1-2: Lenovo ThinkPad Thunderbolt 4 Smart Dock Gen 2
7500
[ 262.127865] thunderbolt 0000:c6:00.6: 2: failed to enable CL states
[ 262.129297] thunderbolt 0000:c6:00.6: 2: USB3 tunnel creation failed
[ 262.130455] thunderbolt 0000:c6:00.6: 2:1: hop deactivation failed for hop
1, index 8
[ 262.130463] thunderbolt 0000:c6:00.6: path activation failed
[ 262.130573] WARNING: CPU: 0 PID: 4777 at drivers/thunderbolt/path.c:587
tb_path_activate+0x10e/0x4a0 [thunderbolt]
[ 262.130789] tb_tunnel_restart+0x9e/0x190 [thunderbolt]
[ 262.130804] tb_tunnel_pci+0x1ae/0x390 [thunderbolt]
[ 262.130819] authorized_store+0x27b/0x2c0 [thunderbolt]
[ 262.130976] thunderbolt 0000:c6:00.6: 0:5 <-> 2:9 (PCI): activation failed
[ 262.131168] thunderbolt 0000:c6:00.6: 2:9: PCIe tunnel activation failed,
aborting
[ 262.131794] thunderbolt 1-2: device disconnected
== Root cause ==
The regression is in CL (clock latency) state negotiation between the
thunderbolt driver and the Intel Goshen Ridge controller. Repeated failed
connection attempts also leave stale routing table entries in the dock
firmware, requiring a full dock power cycle to recover.
== Workaround ==
Adding thunderbolt.clx=0 to GRUB_CMDLINE_LINUX_DEFAULT disables CL state
negotiation and restores normal operation. A full dock power cycle
(laptop shutdown + dock unplugged from wall for 30s) is required once
to clear accumulated stale state.
Confirmed: /sys/module/thunderbolt/parameters/clx reads N with this
parameter set, and the dock functions correctly.
-- System Information:
Debian Release: 13.5
APT prefers stable-updates
APT policy: (500, 'stable-updates'), (500, 'stable-security'), (500, 'stable')
Architecture: amd64 (x86_64)
Kernel: Linux 6.12.94+deb13-amd64 (SMP w/16 CPU threads; PREEMPT)
Locale: LANG=en_GB.UTF-8, LC_CTYPE=en_GB.UTF-8 (charmap=UTF-8),
LANGUAGE=en_GB:en
Shell: /bin/sh linked to /usr/bin/dash
Init: systemd (via /run/systemd/system)
LSM: AppArmor: enabled
