RE: [BUG] wifi: rtw89: 8922ae: no association until module reload

[Ping-Ke Shih <pkshih@realtek.com>]

Kadir Yavuz Kurt <k.yavuzkurt1@gmail.com> wrote:
> Timing observation (hypothesis, not established)
> ================================================
> 
> The only systematic difference I can see between the failing probe and
> the working one is when it runs relative to Bluetooth initialisation.
> The RTL8922AE is a combo part; the BT function enumerates as USB
> 0bda:8922 and is driven by btusb/btrtl.
> 
> At boot (monotonic timestamps, failing probe):
> 
>     [ 3.018707] Bluetooth: hci0: RTL: rom_version status=0 version=1
>     [ 3.018809] rtw89_8922ae 0000:07:00.0: loaded firmware
>                                            rtw89/rtw8922a_fw-4.bin
>     [ 3.018864] rtw89_8922ae 0000:07:00.0: enabling device (0000 -> 0003)
>     [ 3.019712] Bluetooth: hci0: RTL: loading rtl_bt/rtl8922au_fw.bin
>     [ 3.052054] rtw89_8922ae 0000:07:00.0: chip info CID: 71, CV: 2, ...
>     [ 3.097814] rtw89_8922ae 0000:07:00.0 wlp7s0: renamed from wlan0
>     [ 3.638714] Bluetooth: hci0: RTL: fw version 0x41c0c905
> 
> The entire rtw89 probe (3.018 - 3.098) runs inside the BT firmware
> download (3.019 - 3.639), starting 1 ms after it.

This is a good point. I think you can add rtw89 into blacklist, and
manually load the modules after booting. 

If this works, add a udev rule to delay loading rtw89.

> 
> The working reload, same boot:
> 
>     [53.643379] rtw89_8922ae 0000:07:00.0: loaded firmware
>                                            rtw89/rtw8922a_fw-4.bin
>     [53.675553] rtw89_8922ae 0000:07:00.0: chip info CID: 71, CV: 2, ...
> 
> i.e. 50 s after BT finished initialising.
> 
> I want to be clear that this is only a timing correlation. I have not
> yet tested booting with btusb blacklisted, and I am not claiming the
> two are causally related. It is simply the one difference I could find
> that is present in every failing case and absent in every working one.

RTL8922AE is a WiFi/BT combo card. I think they have interference with
each other when initializing, because they share hardware resource and
race can happen at that time. 

Ping-Ke