RTL8723CS not usable with config from RTL8723BS on PinePhone

RTL8723CS not usable with config from RTL8723BS on PinePhone

[Andrey Skvortsov]

Hi,

commit 'rtl_bt: Add firmware file for the the RTL8723CS Bluetooth
part' [1] has added firmware and configuration file for RTL8723CS. After
switching to it I've noticed, that Bluetooth is only partially
working. 'bluetoothctl show' displays information about controller,
but neither scans, nor connection to external devices work. That was
tested with unpatched Linux kernel v6.12-rc6 and rc7 on PinePhone.

Previously I had working BT with firmware from [2]. I've tried to
investigate the problem using rtlfw tool from bluez repository.

Current rtl8723bs_config.bin contains following configuration:

```
$ rtlfw ./rtl8723bs_config.bin
Analyzing ./rtl8723bs_config.bin
Signature: 0x8723ab55
Data len:  58
len=6   offset=002b,{ 00 00 00 aa bb cc }
len=3   offset=00f4,{ 01 00 00 },PCM_SETTING
len=2   offset=00f8,{ 85 00 }
len=1   offset=0027,{ 67 }
len=16  offset=000c,{ 02 80 92 04 50 c5 ea 19 e1 1b f1 af 5f 01 a4 0b },UART_CONFIG
len=1   offset=01df,{ 01 }
len=1   offset=00fe,{ 01 }
len=1   offset=01e3,{ 00 }
len=0   offset=0000,{ }
```

I've tried to modify rtl8723bs_config.bin and after removing following
config section Bluetooth started to work again.

```
len=1   offset=00fe,{ 01 }
```

Unfortunately there is no documentation from Realtek about these
values. Could someone from the company comment about that? Could we
get official configuration for RTL8723CS or should I submit modified
rtl8723bs_config.bin?


1. https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/commit/?id=ed9c1349f8ebae720f3572ad3e74af59bfe345d7
2. https://sources.debian.org/src/rtl8723bt-firmware/20181104-4/rtl_bt/


-- 
Best regards,
Andrey Skvortsov