Arch Linux

Running on a Lenovo Thinkpad P1 connected with a Logitech MX-Ergo trackball through the computer's own bluetooth card (not using the USB dongle provided by Logitech).

After my last update I loose my bluetooth connection with my trackball every time after I put my computer to sleep and after a poweroff of reboot cycle, and I need to re-pair my trackball with bluetoothctl -> scan on and a long button press on the trackball every time.

I tried downgrading several packages (bluez-qt, broadcom-wl), but ultimately what worked was downgrading the kernel to linux-5.8.14.arch1-1 with:

pacman -U /var/cache/pacman/pkg/linux-5.8.14.arch1-1-x86_64.pkg.tar.zst /var/cache/pacman/pkg/virtualbox-host-modules-arch-6.1.14-9-x86_64.pkg.tar.zst

I am now running this downgraded kernel with all the other packages back to the latest version, and everything works as it should.

Steps to reproduce (also see below, and attached journalctl/dmesg):

With linux-5.9.1.arch1-1-1-x86_64
-- with the Logitech MX-Ergo previously paired via bluetoothctl.
-- poweroff and back on or reboot or sleep (or also # systemctl restart bluetooth)
-> then the trackball is lost, and I need to pair it again !

-If I then type:
$ systemctl status bluetooth
I get:
● bluetooth.service - Bluetooth service
Loaded: loaded (/usr/lib/systemd/system/bluetooth.service; enabled; vendor preset: disabled)
Active: active (running) since Mon 2020-10-19 17:14:33 CST; 1min 58s ago
Docs: man:bluetoothd(8)
Main PID: 818 (bluetoothd)
Status: "Running"
Tasks: 1 (limit: 37810)
Memory: 2.8M
CGroup: /system.slice/bluetooth.service
└─818 /usr/lib/bluetooth/bluetoothd

Oct 19 17:14:33 thor bluetoothd[818]: src/main.c:parse_controller_config() Key file does not have group “Controller”
Oct 19 17:14:33 thor bluetoothd[818]: src/main.c:parse_controller_config() Key file does not have group “Controller”
Oct 19 17:14:33 thor bluetoothd[818]: src/main.c:parse_controller_config() Key file does not have group “Controller”
Oct 19 17:14:33 thor bluetoothd[818]: src/main.c:parse_controller_config() Key file does not have group “Controller”
Oct 19 17:14:33 thor bluetoothd[818]: src/main.c:parse_controller_config() Key file does not have group “Controller”
Oct 19 17:14:33 thor bluetoothd[818]: src/main.c:parse_controller_config() Key file does not have group “Controller”
Oct 19 17:14:33 thor bluetoothd[818]: src/main.c:parse_controller_config() Key file does not have group “Controller”
Oct 19 17:14:33 thor systemd[1]: Started Bluetooth service.
Oct 19 17:14:33 thor bluetoothd[818]: Starting SDP server
Oct 19 17:14:34 thor bluetoothd[818]: Bluetooth management interface 1.18 initialized