From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 05C6B3101B6 for ; Wed, 10 Jun 2026 08:56:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781081766; cv=none; b=FsuojZmaL4ETm7qoTPG/FBY7iCpGfGyktmPcuDHCcy7HkIOmlYURGg2VK1o/Z29m4nqSeSwPAuBVrYyeqbHEulPWdeZG6bGnaVSjC3+iG0gL1DfeHjJqe2YuF3tFLXdavszwfI3+d/b1n4JaMOuxYNNV6LphMQEMZD6hcdR2d94= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781081766; c=relaxed/simple; bh=SyNZmYlHx0Bi6bq5xYZEpI+lS1TJKQeiCQ2PVJke7Ng=; h=From:To:Subject:Date:Message-ID:Content-Type:MIME-Version; b=Rr4l6pFomQ09EsolJoU3fIZcwFDpdHa5jeyupwXxERUNqV7ztEQxJJWpX9D/pfksxTkG0JofE7Mgj5rH7hU4G6jf4d6iKX9VDsVidjKvOxihuLb7kCPOEIXz7xq1GYbZ64ElVmwQpiS51istnLT7u/5w8aO1b820yvqZ/Y0DsI4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=X+HIT1T0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="X+HIT1T0" Received: by smtp.kernel.org (Postfix) with ESMTPS id C0C7AC2BCB9 for ; Wed, 10 Jun 2026 08:56:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1781081765; bh=SyNZmYlHx0Bi6bq5xYZEpI+lS1TJKQeiCQ2PVJke7Ng=; h=From:To:Subject:Date:From; b=X+HIT1T00jWP6YqCh0dkjwHG51i7fwZo9T82Y4w9IgL+m/C2eEv0NNleoNMtFDntc taaz6mcWLoZZ9+VOF14Ori9pNkcXrsMYGdHROToZ4ko9Ow3qCHUKo2xYx461jCDahO Lkcy/9sE1EVb52/2VDTrEYHrrMbcuIv80jbXsVZmOVfcu3O4RDBxrXy+LRg1PXsu93 OP+Fg5gSrcWDSrLYeCaMIfmhmCMq9qc0t0Z21WkgoEAAXwoZcMo1oRmp+lUBmk1bGz 3OORJVCHqrKbzWCB2t1iXa4bux6cE9BJXhw0fz94ExD5JeCQL25z4DBng9vBZENGMc CIWb2umdmPA8g== Received: by aws-us-west-2-korg-bugzilla-1.web.codeaurora.org (Postfix, from userid 48) id AEE55C41612; Wed, 10 Jun 2026 08:56:05 +0000 (UTC) From: bugzilla-daemon@kernel.org To: linux-usb@vger.kernel.org Subject: [Bug 221633] New: thunderbolt: hard system freeze from repeated DP tunnel activation failures (LG UltraFine 5K dual-tile + active TB3 cable, Meteor Lake-P) Date: Wed, 10 Jun 2026 08:56:05 +0000 X-Bugzilla-Reason: None X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: AssignedTo drivers_usb@kernel-bugs.kernel.org X-Bugzilla-Product: Drivers X-Bugzilla-Component: USB X-Bugzilla-Version: 2.5 X-Bugzilla-Keywords: X-Bugzilla-Severity: high X-Bugzilla-Who: allan.petersen@vocast.com X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P3 X-Bugzilla-Assigned-To: drivers_usb@kernel-bugs.kernel.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version rep_platform op_sys bug_status bug_severity priority component assigned_to reporter cf_regression Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: https://bugzilla.kernel.org/ Auto-Submitted: auto-generated Precedence: bulk X-Mailing-List: linux-usb@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 https://bugzilla.kernel.org/show_bug.cgi?id=3D221633 Bug ID: 221633 Summary: thunderbolt: hard system freeze from repeated DP tunnel activation failures (LG UltraFine 5K dual-tile + active TB3 cable, Meteor Lake-P) Product: Drivers Version: 2.5 Hardware: Intel OS: Linux Status: NEW Severity: high Priority: P3 Component: USB Assignee: drivers_usb@kernel-bugs.kernel.org Reporter: allan.petersen@vocast.com Regression: No SUMMARY Connecting an LG UltraFine 5K (dual-tile Thunderbolt 3 display, internal Ti= tan Ridge JHL7540) to a Meteor Lake-P host with the display's stock active TB3 cable causes the TB link to flap in a tight loop (connect -> tunnel activat= ion failures -> disconnect, every ~3 s). After seconds to minutes of this churn= the machine hard-freezes (no oops reaches the journal, no pstore record; only a power cycle recovers it). Reproduced on two kernels: - 6.17.0-35-generic (Ubuntu 24.04 HWE) - froze twice - 6.19.14 mainline (kernel.ubuntu.com build) - froze once; additionally emi= ts a repeating WARN at drivers/thunderbolt/path.c:589 in tb_path_activate() A freeze triggered by a misbehaving/marginal external device + cable is sti= ll a host-side robustness bug: hotplug churn should never take down the machine. HARDWARE - Host: Lenovo ThinkPad T14 Gen 5 (21MLCTO1WW), BIOS N47ET28W (1.17), 12/05/2025 - TB controller: Intel Meteor Lake-P Thunderbolt 4 NHI #0/#1 [8086:7ec2 / 8086:7ec3] - Display: LG UltraFine 5K (TB vendor 0x1e, device 0x1114; internal Intel JHL7540 Titan Ridge bridge [8086:15ef]); dual-tile 2x 2560x2880 - Cable: LG's bundled active TB3 cable (trigger); reproduced with two diffe= rent LG cables and three different UltraFine 5K units, on both host TB ports - Secure Boot disabled; no out-of-tree modules FAILURE SIGNATURE (each ~3 s cycle) thunderbolt 0-1: new device found, vendor=3D0x1e device=3D0x1114 thunderbolt 0-1: LG Electronics UltraFine 5K thunderbolt 0000:00:0d.2: 1: failed to enable CL states thunderbolt 0000:00:0d.2: 1:1: hop deactivation failed for hop 1, index 8 thunderbolt 0000:00:0d.2: PCIe Down path activation failed: -107 thunderbolt 0000:00:0d.2: 0:8 <-> 1:8 (PCI): activation failed thunderbolt 0000:00:0d.2: 1:8: PCIe tunnel activation failed, aborting thunderbolt 0000:00:0d.2: 1:10: DP tunnel activation failed, aborting thunderbolt 0-1: device disconnected The 6.19.14 boot that froze contains 84 "DP tunnel activation failed" lines= in ~21 minutes. Other recurring messages: thunderbolt 0000:00:0d.2: 0:5 <-> 1:10 (DP): not enough bandwidth available thunderbolt 0000:00:0d.2: 0:5: timeout waiting for DPTX request to clear thunderbolt 0000:00:0d.2: 0:5 <-> 1:10 (DP): failed to change bandwidth allocation thunderbolt 0-0:1.1: failed to add NVM devices: -19 i915 0000:00:02.0: [drm] *ERROR* [CONNECTOR:280:DP-1][ENCODER:279:DDI TC1/P= HY TC1][DPRX] Can't reduce link training parameters after failure WARN ON 6.19.14 (repeats on every flap cycle) WARNING: drivers/thunderbolt/path.c:589 at tb_path_activate+0x118/0x540 [thunderbolt] Workqueue: thunderbolt0 tb_handle_hotplug [thunderbolt] RIP: 0010:tb_path_activate+0x121/0x540 [thunderbolt] tb_tunnel_activate+0xba/0x2e0 [thunderbolt] tb_tunnel_one_dp+0x29d/0x3b0 [thunderbolt] tb_tunnel_dp+0xbb/0x300 [thunderbolt] tb_dp_resource_available+0xda/0x250 [thunderbolt] tb_handle_hotplug+0x429/0x770 [thunderbolt] The same WARN also fires via tb_domain_approve_switch / authorized_store (b= oltd authorization path) - full splat attached. After many plug cycles the Type-C side also corrupts: sysfs: cannot create duplicate filename '/devices/platform/USBC000:00/typec/port1/port1.2/partner' typec_displayport port1-partner.1: probe with driver typec_displayport fail= ed with error -17 FREEZE TIMELINE (6.19.14) - 09:01:18 LG connected, DP tunnel "not enough bandwidth", flap loop resum= es - 09:01:46 last journal line (thunderbolt 0-1: device disconnected) - Machine completely unresponsive (UI, keyboard); no oops/panic captured; h= ard power-off required. Same pattern on 6.17.0-35 (froze 08:17 same day). WORKAROUNDS TESTED (no effect) - thunderbolt.clx=3D0 - removes "failed to enable CL states", tunnels still= fail - thunderbolt.bw_alloc_mode=3D0 - no change - Both host TB ports, multiple LG cables/units - identical behaviour WHAT WORKS (isolation data) - Same LG display + certified TB4/USB4 cable (Apple Thunderbolt cable): link comes up at 40 Gb/s and is fully stable - dual-tile 5K, PCIe tunnel (displa= y's JHL7540 + xHCI visible), no errors. So the trigger is the active TB3 cable + Meteor Lake USB4 host combination. - Apple Studio Display works flawlessly on the same host - including through the LG active TB3 cable. The flap only occurs with LG display + LG cable. - The LG display + LG cable combination works normally on macOS hosts. EXPECTED BEHAVIOUR Repeated tunnel activation failures from a marginal link should result in t= he device being dropped/ignored (rate-limited retries), not an unbounded connect/teardown loop that eventually hard-freezes the host. Full kernel logs from both freeze boots, the complete WARN splat and lspci inventory are attached. Happy to test patches or provide further debug outp= ut (thunderbolt.dyndbg). Bisection between 6.17 and 6.19 is not possible since both fail. --=20 You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.=