Bluetooth Audio Stuttering During WiFi Activity on RTL8852CE
UPDATE: I’ve found that kernel 6.11.4 works perfectly while 6.12.9 has the audio stuttering issue. Detailed analysis and findings in this comment.
System Information
- OS: Fedora Linux 41 (Workstation Edition)
- Kernel: 6.12.8-200.fc41.x86_64
- Hardware:
- Lenovo IdeaPad Slim 5 14AHP9 (Model: 83DB)
- BIOS: LENOVO NGCN26WW (05/27/2024)
- CPU: AMD Ryzen 7 8845HS w/ Radeon 780M Graphics
- Memory: 28 GiB (12.2% used)
- Audio Stack:
- PipeWire v1.2.7 (active)
- ALSA v: k6.12.8-200.fc41.x86_64
Network Hardware
- WiFi/BT Controller: Realtek RTL8852CE PCIe 802.11ax
- Driver: rtw89_8852ce (kernel version)
- Bus ID: 02:00.0
- Bluetooth:
- Realtek Bluetooth Radio
- Driver: btusb v0.8
- Bus ID: 1-5:3
- Bluetooth version: 5.3
- LMP version: 12
Audio Device
- Device: AirPods Pro (AA:55:24:08:F8:F2)
- Audio Profiles: A2DP (Sink), HFP
- Class: 0x00240418
- Supported UUIDs: Audio Sink, A/V Remote Control, Handsfree
Connection Details
- WiFi: 5GHz band (5500 MHz), VHT-MCS 9 80MHz, Signal -55 dBm
- Operating Environment: GNOME 47.2 on Wayland
Issue Description
When using Bluetooth audio while WiFi is active:
- Audio stutters during network activity (both upload and download)
- Problem occurs with both AAC and SBC codecs
- Stuttering is intermittent, typically after initial 1-2 seconds of network activity
- Issue disappears when WiFi is disabled
- WiFi events show RSSI drops to -110 dBm during stutters
- Problem affects AirPods Pro (AAC codec) and has been observed with other Bluetooth audio devices (SBC codec)
To Reproduce
- Connect Bluetooth audio device
- Start audio playback (e.g., Spotify, YouTube)
- Initiate network activity (e.g., start a download or speed test)
- Audio will stutter/skip during network activity
Diagnostic Logs
During stuttering events:
> journalctl -f
Jan 12 15:52:46 fedora wpa_supplicant[1270]: wlp2s0: CTRL-EVENT-SIGNAL-CHANGE above=1 signal=-56 noise=9999 txrate=468000
> sudo iw event
wlp2s0 (phy #4): CQM event: RSSI (-110 dBm) went above threshold
Debug Information
journalctl
during module reload shows:
kernel: rtw89_8852ce 0000:02:00.0: [RX_DCK] S1 RXDCK timeout
Attempted Solutions
- Modified Bluetooth connection parameters:
MinConnectionInterval=7
MaxConnectionInterval=9
SlaveLatency=0
ConnectionSupervisionTimeout=400
- Modified WiFi/Bluetooth coexistence settings:
options rtw89_pci disable_ps_mode=1
options rtw89_core coex_bt_rssi_th=70
- Disabled power saving features
None of these solutions fully resolved the issue.
Additional Notes
- No stuttering occurs when using ethernet with WiFi disabled
- Issue persists across different Bluetooth codecs
- Both WiFi and Bluetooth are part of the same RTL8852CE chip
- Device presents Bluetooth through internal USB interface despite being integrated
- GTK uses TKIP while PTK uses CCMP, possibly indicating a suboptimal router configuration
Environment Details
$ lspci -nnk | grep -A3 Network
02:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. RTL8852CE PCIe 802.11ax Wireless Network Controller [10ec:c852] (rev 01)
Subsystem: Lenovo Device [17aa:5852]
Kernel driver in use: rtw89_8852ce
Kernel modules: rtw89_8852ce
Questions
- Are there known issues with RTL8852CE WiFi/Bluetooth coexistence?
Are there firmware updates available that might address this?- Could this be related to the RX_DCK timeout issues observed in the logs?
- Are there additional debugging steps or logs that would be helpful?
Please let me know if you need any additional information or would like me to run specific tests.