[Issue Report] Realtek 8852AE Bluetooth audio issues while using WiFi

[Issue Report] Realtek 8852AE Bluetooth audio issues while using WiFi

[Muhammad Usama Anjum]

Hi,

I'm running 6.1.0-3 kernel and getting Bluetooth audio glitches constantly
on a pair of buds and all the time when WiFi is connecting and working on
RTL 8852AE card. Some Bluetooth audio devices work fine without issue. But
some devices get glitchy audio all the time when Wifi is being used. The
audio becomes more and more glitchy as the WiFi use increases. [1] mentions
that the problem for Realtek 8723BE gets solved by switching to 5GHz wifi
or upgrading drives. Is this issue present on other operating systems for
this chip as well? Can it be solved for Linux if Wifi is used at 2.4 GHz?

Any pointers on this problem would be much appreciated.

04:00.0 Network controller: Realtek Semiconductor Co., Ltd. RTL8852AE
802.11ax PCIe Wireless Network Adapter
        Subsystem: Lenovo RTL8852AE 802.11ax PCIe Wireless Network Adapter
        Control: I/O+ Mem+ BusMaster+ SpecCycle- MemWINV- VGASnoop- ParErr-
Stepping- SERR- FastB2B- DisINTx+
        Status: Cap+ 66MHz- UDF- FastB2B- ParErr- DEVSEL=fast >TAbort-
<TAbort- <MAbort- >SERR- <PERR- INTx-
        Latency: 0, Cache Line Size: 64 bytes
        Interrupt: pin A routed to IRQ 100
        IOMMU group: 15
        Region 0: I/O ports at 1000 [size=256]
        Region 2: Memory at d1700000 (64-bit, non-prefetchable) [size=1M]
        Capabilities: <access denied>
        Kernel driver in use: rtw89_8852ae
        Kernel modules: rtw89_8852ae

[1] https://wiki.archlinux.org/title/bluetooth_headset

-- 
BR,
Muhammad Usama Anjum

RE: [Issue Report] Realtek 8852AE Bluetooth audio issues while using WiFi

[Ping-Ke Shih]

> -----Original Message-----
> From: Muhammad Usama Anjum <usama.anjum@collabora.com>
> Sent: Tuesday, February 14, 2023 4:38 AM
> To: Ping-Ke Shih <pkshih@realtek.com>; Kalle Valo <kvalo@kernel.org>; David S. Miller <davem@davemloft.net>;
> Eric Dumazet <edumazet@google.com>; Jakub Kicinski <kuba@kernel.org>; Paolo Abeni <pabeni@redhat.com>
> Cc: Muhammad Usama Anjum <usama.anjum@collabora.com>; netdev@vger.kernel.org;
> linux-kernel@vger.kernel.org; linux-wireless@vger.kernel.org
> Subject: [Issue Report] Realtek 8852AE Bluetooth audio issues while using WiFi
> 
> Hi,
> 
> I'm running 6.1.0-3 kernel and getting Bluetooth audio glitches constantly
> on a pair of buds and all the time when WiFi is connecting and working on
> RTL 8852AE card. Some Bluetooth audio devices work fine without issue. But
> some devices get glitchy audio all the time when Wifi is being used. The
> audio becomes more and more glitchy as the WiFi use increases. [1] mentions
> that the problem for Realtek 8723BE gets solved by switching to 5GHz wifi
> or upgrading drives. Is this issue present on other operating systems for
> this chip as well? Can it be solved for Linux if Wifi is used at 2.4 GHz?

Bluetooth devices work on 2.4 GHz, so the coexistence mechanism on this band
is more difficult than 5 GHz. That is why [1] suggest to switch to 5GHz.

To debug this problem, please follow below steps to capture log and send them
to me privately. I will forward them to the person who is familiar with 
WiFi and BT coexistence.

The directory of debug entry is like /sys/kernel/debug/ieee80211/phy0/rtw89
Use below shell command to capture log periodically during BT gets glitch,
$ while [ 1 ]; do date -R; cat /sys/kernel/debug/ieee80211/phy0/rtw89/btc_info; sleep 2; done | tee xxx.log 

Please provide separate logs for each Bluetooth device with/without glitch,
and give us simple descriptions about timestamp and symptom, like
"at time 09:10 Bluetooth device gets glitch when WiFi is downloading file"
That can help us to address problem quickly. Please only pair only one
Bluetooth device when capturing log.

Ping-Ke