I am unable to find bluetooth devices after switching on. The device to be connected works well with my mobile and my older machine. I am using Ubuntu 20.04.5 LTS.
$ lspci -knn | grep Net -A3; lsusb
01:00.0 Network controller [0280]: Realtek Semiconductor Co., Ltd. Device [10ec:b852]
DeviceName: Realtek Wireless LAN + BT
Subsystem: Hewlett-Packard Company Device [103c:88e3]
Kernel driver in use: rtl8852be
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 001 Device 003: ID 0bda:b85c Realtek Semiconductor Corp. Bluetooth Radio
Bus 001 Device 002: ID 05c8:0b04 Cheng Uei Precision Industry Co., Ltd (Foxlink) HP Wide Vision HD Camera
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
$ systemctl | grep -i blue
sys-devices-pci0000:00-0000:00:08.1-0000:03:00.3-usb1-1\x2d4-1\x2d4:1.0-bluetooth-hci0.device loaded active plugged /sys/devices/pci0000:00/0000:00:08.1/0000:03:00.3/usb1/1-4/1-4:1.0/bluetooth/hci0
sys-subsystem-bluetooth-devices-hci0.device loaded active plugged /sys/subsystem/bluetooth/devices/hci0
bluetooth.service loaded active running Bluetooth service
bluetooth.target loaded active active Bluetooth
$ dmesg | grep -i blue
[ 1.930607] usb 1-4: Product: Bluetooth Radio
[ 2.692372] Bluetooth: Core ver 2.22
[ 2.692618] NET: Registered PF_BLUETOOTH protocol family
[ 2.692620] Bluetooth: HCI device and connection manager initialized
[ 2.692625] Bluetooth: HCI socket layer initialized
[ 2.692628] Bluetooth: L2CAP socket layer initialized
[ 2.692632] Bluetooth: SCO socket layer initialized
[ 2.836399] Bluetooth: hci0: RTL: examining hci_ver=0b hci_rev=000b lmp_ver=0b lmp_subver=8852
[ 2.836404] Bluetooth: hci0: RTL: unknown IC info, lmp subver 8852, hci rev 000b, hci ver 000b
[ 2.836408] Bluetooth: hci0: RTL: assuming no firmware upload needed
[ 4.131674] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[ 4.131680] Bluetooth: BNEP filters: protocol multicast
[ 4.131687] Bluetooth: BNEP socket layer initialized
[ 12.760766] Bluetooth: RFCOMM TTY layer initialized
[ 12.760777] Bluetooth: RFCOMM socket layer initialized
[ 12.760783] Bluetooth: RFCOMM ver 1.11
[ 184.779533] Bluetooth: hci0: RTL: examining hci_ver=0b hci_rev=000b lmp_ver=0b lmp_subver=8852
[ 184.779543] Bluetooth: hci0: RTL: unknown IC info, lmp subver 8852, hci rev 000b, hci ver 000b
[ 184.779546] Bluetooth: hci0: RTL: assuming no firmware upload needed
[ 477.986714] Bluetooth: hci0: RTL: examining hci_ver=0b hci_rev=000b lmp_ver=0b lmp_subver=8852
[ 477.986725] Bluetooth: hci0: RTL: unknown IC info, lmp subver 8852, hci rev 000b, hci ver 000b
[ 477.986729] Bluetooth: hci0: RTL: assuming no firmware upload needed
[ 1729.638529] Bluetooth: hci0: RTL: examining hci_ver=0b hci_rev=000b lmp_ver=0b lmp_subver=8852
[ 1729.638541] Bluetooth: hci0: RTL: unknown IC info, lmp subver 8852, hci rev 000b, hci ver 000b
[ 1729.638546] Bluetooth: hci0: RTL: assuming no firmware upload needed
$ rfkill list all
1: phy0: Wireless LAN
Soft blocked: no
Hard blocked: no
4: hci0: Bluetooth
Soft blocked: no
Hard blocked: no
$ sudo apt list | grep "bluez\|blueman"
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
blueman/focal-updates 2.1.2-1ubuntu0.3 amd64
bluez-btsco/focal 1:0.50-0ubuntu7 amd64
bluez-cups/focal-updates,focal-security,now 5.53-0ubuntu3.6 amd64 [installed,automatic]
bluez-dbg/focal-updates,focal-security 5.53-0ubuntu3.6 amd64
bluez-dbg/focal-updates,focal-security 5.53-0ubuntu3.6 i386
bluez-hcidump/focal-updates,focal-security 5.53-0ubuntu3.6 amd64
bluez-hcidump/focal-updates,focal-security 5.53-0ubuntu3.6 i386
bluez-obexd/focal-updates,focal-security,now 5.53-0ubuntu3.6 amd64 [installed,automatic]
bluez-obexd/focal-updates,focal-security 5.53-0ubuntu3.6 i386
bluez-tests/focal-updates,focal-security 5.53-0ubuntu3.6 amd64
bluez-tests/focal-updates,focal-security 5.53-0ubuntu3.6 i386
bluez-tools/focal 2.0~20170911.0.7cb788c-2build1 amd64
bluez/focal-updates,focal-security,now 5.53-0ubuntu3.6 amd64 [installed,automatic]
bluez/focal-updates,focal-security 5.53-0ubuntu3.6 i386
libkf5bluezqt-data/focal,focal 5.68.0-0ubuntu1 all
libkf5bluezqt-dev/focal 5.68.0-0ubuntu1 amd64
libkf5bluezqt-doc/focal,focal 5.68.0-0ubuntu1 all
libkf5bluezqt6/focal 5.68.0-0ubuntu1 amd64
python-bluez/focal 0.22+really0.22-1build2 amd64
python3-bluez/focal 0.22+really0.22-1build2 amd64
qml-module-org-kde-bluezqt/focal 5.68.0-0ubuntu1 amd64
Attempt 1
I tried removing and loading btusb module (as suggested here: https://askubuntu.com/a/1267032/1384407), but the issue persists.
Attempt 2
I also tried installing blueman and rtbth-dkms as suggested here https://askubuntu.com/a/1238076/1384407. After rebooting, I get the following error when I start blueman-manager.
$ sudo blueman-manager
blueman-manager version 2.1.2 starting
Failed to enable bluetooth
Moreover, I get also get the error Open dev fail: No such device or address when I run sudo modprobe rtbth.
Note
Don't know if this is related but my WiFi was not working as well and I had followed this answer to get it working: https://askubuntu.com/a/1415950/1384407.
