[Bug 221309] New: rtl8822cu: BLE disconnects with firmware 0x0673_0EDC regression

[bugzilla-daemon@kernel.org]

https://bugzilla.kernel.org/show_bug.cgi?id=221309

            Bug ID: 221309
           Summary: rtl8822cu: BLE disconnects with firmware 0x0673_0EDC
                    regression
           Product: Drivers
           Version: 2.5
          Hardware: AMD
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P3
         Component: Bluetooth
          Assignee: linux-bluetooth@vger.kernel.org
          Reporter: i+kernel.org@schimpf.link
        Regression: No

Created attachment 309794
  --> https://bugzilla.kernel.org/attachment.cgi?id=309794&action=edit
stability log after downgrade

Overview

After updating linux-firmware-realtek to 20260221-1 (which includes commit
fbf93476,
"update rtl8822c bt usb and uart firmware to 0x0673"), the RTL8822CU USB
Bluetooth adapter
(0bda:b00c) begins dropping BLE connections every few minutes. Each disconnect
lasts several seconds before the device reconnects. The adapter itself never
resets and
the USB device remains active throughout. Only the BLE link is lost.

Steps to Reproduce

1. Use a system with an RTL8822CU USB Bluetooth adapter (0bda:b00c).
2. Pair and connect a BLE HID device (tested: Logitech M585/M590 mouse).
3. Optionally connect a second BLE HID device simultaneously (tested:
HHKB-Hybrid_2 keyboard).
4. Use the BLE device normally. No special interaction required, disconnects
occur at idle and
   during active use.

Actual Results

The BLE mouse disconnects often (observed 13+ times over 60 minutes).
bluetoothd reports
Connected: false on the device D-Bus object, the kernel destroys and recreates
the UHID device
on reconnect, and the mouse is unresponsive for the duration. Downtime can be
multiple seconds.
No kernel messages are produced during the disconnect. The second BLE device
(HHKB keyboard)
is unaffected.

dbus-monitor confirms the disconnect is hardware-initiated.

Expected Results

The BLE connection should remain stable during normal use, as it did with the
previous firmware.

Build Date & Hardware

  Offending firmware: rtl_bt/rtl8822cu_fw.bin, version 0x0673_0EDC, introduced
in commit
    fbf93476b78933a87073d3bf116a84f2599b37b5 (2026-02-02)
  Adapter: Realtek RTL8822CU, USB ID 0bda:b00c
  Kernel: 6.19.10-arch1-1
  bluetoothd: 5.86
  OS: Arch Linux

Additional Builds and Platforms

Does not occur with rtl_bt/rtl8822cu_fw.bin from tag 20260110 (the commit
immediately
preceding fbf93476). Downgrading to that firmware eliminates all disconnects.

Additional Information

USB autosuspend was ruled out by polling
/sys/bus/usb/devices/1-3/power/runtime_status and
runtime_suspended_time during a live disconnect. The adapter remained active
throughout.
The disconnect also happens while actively moving the mouse. 
Everything tested with default Bluetooth settings.

I'm currently downgrading linux-firmware-realtek to 20260110-1 as a workaround.

I'm running two linux user accounts in parallel, one at tty1 and one at tty2.

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