bluetooth hci0 firmware failed to load rtl_bt/rtl8723b_config.bin

[itmagpro]

$ uname -a
Linux falian 6.1.0-23-rt-686-pae #1 SMP PREEMPT_RT Debian 6.1.99-1 (2024-07-15) i686 GNU/Linux

driver compiled from rtl8723bu-master_20250122.zip

firmware installed

firmware-realtek - Binary firmware for Realtek wired/wifi/BT adapters
firmware-realtek-rtl8723cs-bt - Bluetooth firmware for Realtek RTL8723CS

bluetooth not work, full dmesg output: https://pastebin.com/qrU8AzHv

[Пт фев 21 18:03:59 2025] Bluetooth: hci0: RTL: rom_version status=0 version=1
[Пт фев 21 18:03:59 2025] Bluetooth: hci0: RTL: loading rtl_bt/rtl8723b_fw.bin
[Пт фев 21 18:03:59 2025] bluetooth hci0: firmware: direct-loading firmware rtl_bt/rtl8723b_fw.bin
[Пт фев 21 18:03:59 2025] Bluetooth: hci0: RTL: loading rtl_bt/rtl8723b_config.bin
[Пт фев 21 18:03:59 2025] bluetooth hci0: firmware: failed to load rtl_bt/rtl8723b_config.bin (-2)
[Пт фев 21 18:03:59 2025] firmware_class: See https://wiki.debian.org/Firmware for information about missing firmware
[Пт фев 21 18:03:59 2025] bluetooth hci0: firmware: failed to load rtl_bt/rtl8723b_config.bin (-2)
[Пт фев 21 18:03:59 2025] bluetooth hci0: Direct firmware load for rtl_bt/rtl8723b_config.bin failed with error -2
[Пт фев 21 18:03:59 2025] Bluetooth: hci0: RTL: cfg_sz -2, total sz 22496
[Пт фев 21 18:03:59 2025] Bluetooth: hci0: RTL: fw version 0x0e2f9f73

UPD
recompilation without CONFIG_CONCURRENT_MODE seems to fix issues and bluetooth work now

but what with missing rtl8723b_config.bin?

[Yelinz]

ln -sf /lib/firmware/rtl_bt/rtl8723bs_config.bin /lib/firmware/rtl_bt/rtl8723b_config.bin

Thats what I did, seems to work without this firmware repo or the fork https://github.com/Benetti-Engineering/rtl8723bu
Installing the firmware repo didnt seem to make any difference.

YMMV

But I would be interested in the real fix, as I've also had to add some bluetooth modprobe options to get the usb dongle to work.
Havent tested only setting modprobe without the softlink, if bluetooth still works then.