Public bug reported:
Bluetooth fails to initialize on kernel 6.8.0-139-generic. The kernel
logs a NULL pointer dereference during MediaTek Bluetooth firmware
setup. Rebooting into 6.8.0-138-generic restores Bluetooth
functionality.
## Hardware and system
- Ubuntu 24.04.4 LTS, x86_64
- Lenovo 21A4 / LNVNB161216
- BIOS GQCN45WW(V1.31), 2024-10-22
- Bluetooth USB ID: 0489:e0cd (Foxconn / Hon Hai MediaTek)
- Failing kernel: 6.8.0-139.139
- Working kernel: 6.8.0-138.138
## Reproduction on affected hardware
1. Boot kernel 6.8.0-139-generic on the machine above.
2. Bluetooth initialization fails during boot. `bluetoothctl show` reports `No
default controller available`.
3. Boot 6.8.0-138-generic on the same machine. The controller initializes and
Bluetooth works.
The failure is recorded on two boots with 139 (September 7 and 8). Logs
from 138 show successful initialization before and after those boots.
Other hardware has not been tested.
On 139, the adapter remains visible in lsusb, bluetooth.service is
running, and rfkill shows no Bluetooth blocks.
## Kernel error
```text
BUG: kernel NULL pointer dereference, address: 0000000000000219
Workqueue: hci0 hci_power_on [bluetooth]
RIP: 0010:__pm_runtime_resume+0x1b/0x80
```
Selected call-trace frames:
```text
usb_autopm_get_interface+0x1d/0x60
btmtk_usb_hci_wmt_sync+0xa9/0x2e0 [btmtk]
btmtk_setup_firmware_79xx+0x1ca/0x360 [btmtk]
btusb_mtk_setup+0x453/0x610 [btusb]
hci_dev_setup_sync+0x6f/0x430 [bluetooth]
```
The complete initial oops is attached as `kernel-139-crash.txt`.
## Additional context
This report is prepared while running the working kernel, 138.
Automatically collected system information will describe that kernel.
Firmware packages were updated on September 8 after the captured failing
boot and before the successful reboot into 138. Earlier working and
failing boots both reported adapter firmware build time 20240219111427.
Current firmware package versions therefore do not describe all tested
boots.
## Attachments
- `kernel-139-crash.txt`: initial oops from the failing September 8 boot.
- `kernel-138-bluetooth.txt`: initialization messages from the working
September 8 boot.
- `kernel-139-full.log`: full failing-boot kernel log.
- `kernel-138-full.log`: full working-boot kernel log.
ProblemType: Bug
DistroRelease: Ubuntu 24.04
Package: linux-image-6.8.0-138-generic 6.8.0-138.138
ProcVersionSignature: Ubuntu 6.8.0-138.138-generic 6.8.12
Uname: Linux 6.8.0-138-generic x86_64
ApportVersion: 2.28.3-0ubuntu0.1
Architecture: amd64
AudioDevicesInUse:
USER PID ACCESS COMMAND
/dev/snd/controlC1: andy 4113 F.... wireplumber
/dev/snd/controlC0: andy 4113 F.... wireplumber
/dev/snd/seq: andy 4108 F.... pipewire
CRDA: N/A
CasperMD5CheckResult: unknown
CurrentDesktop: ubuntu:GNOME
Date: Tue Sep 8 11:33:26 2026
InstallationDate: Installed on 2022-02-09 (1672 days ago)
InstallationMedia: Ubuntu 20.04.3 LTS "Focal Fossa" - Release amd64 (20210819)
MachineType: LENOVO 21A4
ProcFB: 0 amdgpudrmfb
ProcKernelCmdLine: BOOT_IMAGE=/boot/vmlinuz-6.8.0-138-generic
root=UUID=ed37ad41-2253-4a1f-80b7-101995dd0714 ro quiet splash vt.handoff=7
RelatedPackageVersions:
linux-restricted-modules-6.8.0-138-generic N/A
linux-backports-modules-6.8.0-138-generic N/A
linux-firmware 20240318.git3b128b60.0ubuntu3.1
SourcePackage: linux
UpgradeStatus: Upgraded to noble on 2024-10-01 (707 days ago)
dmi.bios.date: 10/22/2024
dmi.bios.release: 1.45
dmi.bios.vendor: LENOVO
dmi.bios.version: GQCN45WW(V1.31)
dmi.board.asset.tag: NO Asset Tag
dmi.board.name: LNVNB161216
dmi.board.vendor: LENOVO
dmi.board.version: SDK0J40709 WIN
dmi.chassis.asset.tag: NO Asset Tag
dmi.chassis.type: 10
dmi.chassis.vendor: LENOVO
dmi.chassis.version: ThinkBook 15 G3 ACL
dmi.ec.firmware.release: 1.45
dmi.modalias:
dmi:bvnLENOVO:bvrGQCN45WW(V1.31):bd10/22/2024:br1.45:efr1.45:svnLENOVO:pn21A4:pvrThinkBook15G3ACL:rvnLENOVO:rnLNVNB161216:rvrSDK0J40709WIN:cvnLENOVO:ct10:cvrThinkBook15G3ACL:skuLENOVO_MT_21A4_BU_idea_FM_ThinkBook15G3ACL:
dmi.product.family: ThinkBook 15 G3 ACL
dmi.product.name: 21A4
dmi.product.sku: LENOVO_MT_21A4_BU_idea_FM_ThinkBook 15 G3 ACL
dmi.product.version: ThinkBook 15 G3 ACL
dmi.sys.vendor: LENOVO
** Affects: linux (Ubuntu)
Importance: Undecided
Status: New
** Tags: amd64 apport-bug noble wayland-session
** Attachment added: "zip containing the 4 txt attachments"
https://bugs.launchpad.net/bugs/2166750/+attachment/5998514/+files/kernel-logs.zip
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https://bugs.launchpad.net/bugs/2166750
Title:
[Regression] MediaTek Bluetooth 0489:e0cd fails on 6.8.0-139; works on
6.8.0-138
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