Public bug reported:
# UCSI / USB-C Audio Accessory regression on kernel 7.0.0-15-generic
## Summary
Since first boot of kernel **7.0.0-15-generic**, the UCSI ACPI driver
reports persistent errors and
`/sys/class/typec/port*/supported_accessory_modes` is `none` on all
USB-C ports. As a result, USB-C analog headsets (USB-C Audio Accessory
mode) that previously worked under kernel **7.0.0-14-generic** are no
longer detected at all: the typec partner is registered, but no USB
enumeration and no analog accessory routing occurs.
Devices implementing the USB-C standard with a built-in USB DAC (e.g.
JBL Tune 310C USB-C, USB ID `0ecb:20f6`) still work normally, confirming
the regression is specific to the Audio Accessory mode path / UCSI
capability reporting.
## System
- Machine: Dell Precision 5570 (Alder Lake-P)
- BIOS: 1.40.0 (2026-03-31)
- Distro: Ubuntu 26.04 (Resolute Raccoon)
- Audio stack: PipeWire 1.6.2 + WirePlumber 0.5.13 (not relevant — issue is
below the audio stack)
- USB-C controllers: Intel Alder Lake-P Thunderbolt 4 USB Controller
`8086:461e`, PCH xHCI `8086:51ed`
## Affected kernel
- Working: `7.0.0-14-generic` (`linux-image-7.0.0-14-generic` 7.0.0-14.14)
- Broken: `7.0.0-15-generic` (`linux-image-7.0.0-15-generic` 7.0.0-15.15)
## Timeline (correlates exactly with kernel upgrade)
| Date / time (UTC) | Event |
|---|---|
| Before 2026-05-17 | Running kernel 7.0.0-14, zero UCSI errors in kern.log,
USB-C analog earphones work |
| 2026-05-17 17:34 (CEST 19:34) | dpkg installs/upgrades GRUB 2.14,
shim-signed, dracut, lvm2, cryptsetup, presumably pulls in
`linux-image-7.0.0-15-generic` |
| **2026-05-17 19:49 UTC (21:49 CEST)** | **First boot on 7.0.0-15. First UCSI
errors appear immediately in kern.log:** |
```
ucsi_acpi USBC000:00: unknown error 0
ucsi_acpi USBC000:00: UCSI_GET_PDOS failed (-5)
```
These errors then repeat on every boot since.
## Symptoms
1. `UCSI_GET_PDOS failed (-5)` — the kernel cannot query Power Data Objects
from the UCSI controller.
2. `/sys/class/typec/port{0,1,2}/supported_accessory_modes` = `none` on all
three USB-C ports.
3. USB-C analog headsets (no built-in DAC) plugged into any port: the typec
partner is created (`/sys/class/typec/portN-partner` appears) with no
advertised alt modes, but no USB enumeration occurs and no audio routing.
4. USB-C devices with their own DAC (USB Audio Class) enumerate and work
normally.
## Reproducer
1. Boot kernel 7.0.0-15-generic on a Dell Precision 5570.
2. Plug a USB-C analog headset (no DAC) into any USB-C port (e.g. Wefix
HP-2201A "kit piéton USB-C", or any cheap analog USB-C earbud).
3. Observe:
- `/sys/class/typec/portN-partner` is created.
- No new USB device in `lsusb`.
- No new card in `aplay -l` or `/proc/asound/cards`.
- `/sys/class/typec/portN/supported_accessory_modes` = `none`.
## Expected behaviour
On kernel 7.0.0-14, the same setup detects the headset (or at least
properly reports `supported_accessory_modes` so the analog audio routing
can happen).
## Workaround
Downgrade to `linux-image-7.0.0-14-generic` (still in the `resolute`
archive).
## Files to attach
- `/var/log/kern.log` (or excerpt from the first boot on 7.0.0-15)
- Output of `dmesg | grep -iE 'ucsi|typec'`
- Output of `for p in /sys/class/typec/port*; do echo "$p:"; cat
$p/supported_accessory_modes 2>/dev/null; done`
ProblemType: Bug
DistroRelease: Ubuntu 26.04
Package: linux-image-7.0.0-15-generic 7.0.0-15.15
ProcVersionSignature: Ubuntu 7.0.0-15.15-generic 7.0.0
Uname: Linux 7.0.0-15-generic x86_64
ApportVersion: 2.34.0-0ubuntu2
Architecture: amd64
CasperMD5CheckResult: pass
CurrentDesktop: ubuntu:GNOME
Date: Tue May 26 23:51:26 2026
InstallationDate: Installed on 2026-05-17 (9 days ago)
InstallationMedia: Ubuntu 26.04 "Resolute Raccoon" - Release amd64 (20260423.1)
MachineType: Dell Inc. Precision 5570
ProcEnviron:
LANG=en_US.UTF-8
PATH=(custom, no user)
SHELL=/bin/bash
TERM=xterm-256color
ProcFB: 0 i915drmfb
ProcKernelCmdLine: BOOT_IMAGE=/vmlinuz-7.0.0-15-generic
root=/dev/mapper/ubuntu--vg-ubuntu--lv ro quiet splash
crashkernel=2G-4G:320M,4G-32G:512M,32G-64G:1024M,64G-128G:2048M,128G-:4096M
RebootRequiredPkgs: Error: path contained symlinks.
SourcePackage: linux
UpgradeStatus: No upgrade log present (probably fresh install)
dmi.bios.date: 03/31/2026
dmi.bios.release: 1.40
dmi.bios.vendor: Dell Inc.
dmi.bios.version: 1.40.0
dmi.board.name: 02JH00
dmi.board.vendor: Dell Inc.
dmi.board.version: A00
dmi.chassis.type: 10
dmi.chassis.vendor: Dell Inc.
dmi.ec.firmware.release: 1.19
dmi.modalias:
dmi:bvnDellInc.:bvr1.40.0:bd03/31/2026:br1.40:efr1.19:svnDellInc.:pnPrecision5570:pvr:rvnDellInc.:rn02JH00:rvrA00:cvnDellInc.:ct10:cvr:sku0B1A:pfaPrecision:
dmi.product.family: Precision
dmi.product.name: Precision 5570
dmi.product.sku: 0B1A
dmi.sys.vendor: Dell Inc.
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug resolute
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https://bugs.launchpad.net/bugs/2154322
Title:
[UCSI regression] Dell Precision 5570: UCSI_GET_PDOS failed (-5) and
USB-C Audio Accessory broken since 7.0.0-15
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