need patch from https://patchwork.kernel.org/patch/10728073/ and increased sleep in https://elixir.bootlin.com/linux/v5.0-rc5/source/drivers/soc/mediatek/mtk-scpsys.c#L248

change

usleep_range(12000, 12100);

to

msleep(50);

root@bpi-r64:~# mkdir -p /lib/firmware/mediatek
root@bpi-r64:~# wget https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/plain/mediatek/mt7622pr2h.bin
root@bpi-r64:~# cp mt7622pr2h.bin /lib/firmware/mediatek/
root@bpi-r64:~# apt-get update
root@bpi-r64:~# apt-get install bluez
root@bpi-r64:~# reboot

#boot kernel with applied tty-patch and increased scpsys-sleep