* [Bug 220990] New: hci_uart_bcm: BCM43341 on Intel Atom (serdev) fails init (MTU 0:0, DOWN RAW)
@ 2026-01-18 10:11 bugzilla-daemon
2026-01-19 14:36 ` [Bug 220990] " bugzilla-daemon
0 siblings, 1 reply; 2+ messages in thread
From: bugzilla-daemon @ 2026-01-18 10:11 UTC (permalink / raw)
To: linux-bluetooth
https://bugzilla.kernel.org/show_bug.cgi?id=220990
Bug ID: 220990
Summary: hci_uart_bcm: BCM43341 on Intel Atom (serdev) fails
init (MTU 0:0, DOWN RAW)
Product: Drivers
Version: 2.5
Hardware: Intel
OS: Linux
Status: NEW
Severity: normal
Priority: P3
Component: Bluetooth
Assignee: linux-bluetooth@vger.kernel.org
Reporter: bugzilla@emircanerkul.com
Regression: No
Created attachment 309211
--> https://bugzilla.kernel.org/attachment.cgi?id=309211&action=edit
fix for llm models
I applied solution in https://bugzilla.kernel.org/show_bug.cgi?id=100461
But now it do not detect my devices.
❯ bluetoothctl
hci0 new_settings: powered bondable ssp br/edr le secure-conn
Agent registered
[CHG] Controller CD:74:2E:6E:CD:FA Pairable: yes
[bluetoothctl]> power on
Changing power on succeeded
[bluetoothctl]> discover on
Invalid command in menu main: discover
Use "help" for a list of available commands in a menu.
Use "menu <submenu>" if you want to enter any submenu.
Use "back" if you want to return to menu main.
[bluetoothctl]> he
[bluetoothctl]> scan on
SetDiscoveryFilter success
hci0 type 7 discovering on
Discovery started
[CHG] Controller CD:74:2E:6E:CD:FA Discovering: yes
hci0 type 7 discovering off
hci0 type 7 discovering on
hci0 type 7 discovering off
hci0 type 7 discovering on
hci0 type 7 discovering off
--- ISSUE SOVED WITH 100461 ---
1. Hardware Description
Device: Intel StickPC (Atom x5-Z8300 "Cherry Trail" / "Bay Trail" platform)
Bluetooth/WiFi Chip: Broadcom BCM43341B0 (Combo Chip)
ACPI ID: BCM2E95
Interface: Intel HS-UART connected via serdev (serial0-0)
Connection: UART (not USB)
2. System Information
OS: Debian 13 (Trixie)
Kernel: 6.12.63+deb13-amd64 (Upstream 6.12 series)
BlueZ Version: 5.82
Firmware: BCM43341B0.hcd (Size: 41,333 bytes).
Verified identical to working Windows 10 driver firmware.
3. Issue Description
The Bluetooth controller is detected, and the hci_uart_bcm driver successfully
loads the specific firmware patch (build 0176). However, immediately after
firmware loading, the device remains in a DOWN RAW state with MTU 0:0.
Attempting to bring the device up fails with "Operation not supported". The
device never registers with the BlueZ management layer (btmgmt info is empty).
It appears the HCI_QUIRK_RAW_DEVICE flag (set by hci_serdev.c during setup) is
never cleared, or the bcm_setup function completes but the driver fails to
transition the device to a fully operational state.
4. Steps to Reproduce
Boot minimal Debian 13 with Kernel 6.12 on Intel Atom Z8300 device with
BCM43341.
Ensure correct firmware BCM43341B0.hcd is in /lib/firmware/brcm/.
Check hciconfig -a.
5. Logs & Output
hciconfig -a
hci0: Type: Primary Bus: UART
BD Address: 43:34:1B:00:1F:AC ACL MTU: 0:0 SCO MTU: 0:0
DOWN RAW
RX bytes:2220 acl:0 sco:0 events:238 errors:0
TX bytes:41654 acl:0 sco:0 commands:238 errors:0
Features: 0x00 0x00 0x00 0x00 0x00 0x00 0x00 0x00
Packet type: DM1 DH1 HV1
Link policy:
Link mode: PERIPHERAL ACCEPT
(Note: Address is the default Broadcom address, indicating configuration didn't
finish)
dmesg (Filtered)
[ 10.438792] hci_uart_bcm serial0-0: supply vbat not found, using dummy
regulator
[ 10.438896] hci_uart_bcm serial0-0: supply vddio not found, using dummy
regulator
...
[ 10.888224] Bluetooth: hci0: BCM: chip id 82
[ 10.902831] Bluetooth: hci0: BCM43341B0
[ 10.902851] Bluetooth: hci0: BCM43341B0 (002.001.014) build 0000
[ 10.929324] Bluetooth: hci0: BCM43341B0 'brcm/BCM43341B0.hcd' Patch
...
[ 11.551231] Bluetooth: hci0: BCM43341B0 37.4 MHz Class 1 WLBGA iTR
[ 11.551245] Bluetooth: hci0: BCM43341B0 (002.001.014) build 0176
[ 11.552167] Bluetooth: hci0: BCM: Using default device address
(43:34:1b:00:1f:ac)
(Note: Firmware loads successfully - build number changes from 0000 to 0176.
But then it stops.)
btmgmt info
Index list with 0 items
Attempting to bring up
# hciconfig hci0 up
Can't init device hci0: Operation not supported (95)
6. What Was Tried (Workarounds)
Windows Firmware: Replaced Linux firmware with verified working Windows 10
driver (BCM43341B0_002.001.014.0122.0176.hcd). Result: Identical behavior.
Firmware load OK, Init fail.
Kernel Parameters: Added intel_idle.max_cstate=1 to prevent BayTrail deep sleep
issues. Result: No change.
btattach: Attempted manual btattach but failed because serdev framework claims
the UART (serial0-0) and does not expose a /dev/ttyS* node to userspace even
after unbinding the driver.
7. Suspected Root Cause
Regression in drivers/bluetooth/hci_bcm.c or hci_serdev.c on Kernel 6.12
regarding the handling of HCI_QUIRK_RAW_DEVICE for ACPI-enumerated BCM devices.
The setup phase (firmware load) works, but the transition to operational mode
is missing.
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* [Bug 220990] hci_uart_bcm: BCM43341 on Intel Atom (serdev) fails init (MTU 0:0, DOWN RAW)
2026-01-18 10:11 [Bug 220990] New: hci_uart_bcm: BCM43341 on Intel Atom (serdev) fails init (MTU 0:0, DOWN RAW) bugzilla-daemon
@ 2026-01-19 14:36 ` bugzilla-daemon
0 siblings, 0 replies; 2+ messages in thread
From: bugzilla-daemon @ 2026-01-19 14:36 UTC (permalink / raw)
To: linux-bluetooth
https://bugzilla.kernel.org/show_bug.cgi?id=220990
--- Comment #1 from Erkul (bugzilla@emircanerkul.com) ---
unfortunatelly nothing worked tried a lot of config files. DARK-XSW150.clm_blob
needed. But its really old device and they cant support. Not sure how to
restore bluetooth part..
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You are the assignee for the bug.
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