大家好，我最近遇到了一个蓝牙适配器在Ubuntu 22.04上无法正常工作的问题，想请教一下社区的解决方案：

• 我先入手了Ugreen CM390（蓝牙5.0无天线），这个适配器在Ubuntu上完全免驱，插上去直接就能用，和Windows 10一样不需要手动安装任何驱动或组件（可能系统后台自动处理了驱动，但我没做额外操作）。
• 之后我又买了Ugreen CM749（蓝牙5.4带天线），这个适配器在Windows 10上能正常识别并使用，但在Ubuntu 22.04里却始终无法启用。虽然系统右上角的蓝牙开关显示处于激活状态，但实际搜不到任何设备，也无法被其他设备发现。

补充一下：我有两张状态截图，一张是CM390正常工作的界面，所有功能都没问题；另一张是CM749的状态界面，开关确实在激活位置，但适配器完全不工作。

下面是我收集的两个适配器的系统命令输出，方便大家排查问题：

正常工作的Ugreen CM390（蓝牙5.0）相关输出 #

1. lsusb 命令输出 #

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 c0f4:05e0 SZH usb keyboard
Bus 001 Device 002: ID 2b89:8761 Realtek Bluetooth Radio
Bus 001 Device 004: ID 09da:c10a A4Tech Co., Ltd. USB Mouse
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

2. sudo dmesg|egrep -i 'blue|firm' 命令输出 #

[    0.141167] Spectre V2 : Enabling Speculation Barrier for firmware calls
[    0.346768] ACPI: [Firmware Bug]: BIOS _OSI(Linux) query ignored
[    0.409321] acpi PNP0A08:00: [Firmware Info]: MMCONFIG for domain 0000 [bus 00-3f] only partially covers this bridge
[    1.676838] usb 1-3: Product: Bluetooth Radio
[    4.225739] Bluetooth: Core ver 2.22
[    4.225763] NET: Registered PF_BLUETOOTH protocol family
[    4.225765] Bluetooth: HCI device and connection manager initialized
[    4.225770] Bluetooth: HCI socket layer initialized
[    4.225774] Bluetooth: L2CAP socket layer initialized
[    4.225779] Bluetooth: SCO socket layer initialized
[    4.390769] Bluetooth: hci0: RTL: examining hci_ver=0a hci_rev=000b lmp_ver=0a lmp_subver=8761
[    4.393774] Bluetooth: hci0: RTL: rom_version status=0 version=1
[    4.393781] Bluetooth: hci0: RTL: loading rtl_bt/rtl8761bu_fw.bin
[    4.415884] Bluetooth: hci0: RTL: loading rtl_bt/rtl8761bu_config.bin
[    4.419289] Bluetooth: hci0: RTL: cfg_sz 6, total sz 30210
[    5.166834] Bluetooth: hci0: RTL: fw version 0xdfc6d922
[    6.853668] [drm] Found UVD firmware Version: 1.130 Family ID: 16
[    6.856060] [drm] Found VCE firmware Version: 53.26 Binary ID: 3
[    7.174650] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[    7.174655] Bluetooth: BNEP filters: protocol multicast
[    7.174661] Bluetooth: BNEP socket layer initialized
[    7.177395] Bluetooth: MGMT ver 1.22
[   56.970179] Bluetooth: RFCOMM TTY layer initialized
[   56.970187] Bluetooth: RFCOMM socket layer initialized
[   56.970193] Bluetooth: RFCOMM ver 1.11
[ 5345.185364] Bluetooth: hci0: Opcode 0x1005 failed: -110
[ 5345.185365] Bluetooth: hci0: command 0x1005 tx timeout
[ 6098.391006] Bluetooth: hci0: RTL: examining hci_ver=0a hci_rev=000b lmp_ver=0a lmp_subver=8761
[ 6098.393993] Bluetooth: hci0: RTL: rom_version status=0 version=1
[ 6098.393999] Bluetooth: hci0: RTL: loading rtl_bt/rtl8761bu_fw.bin
[ 6098.394415] Bluetooth: hci0: RTL: loading rtl_bt/rtl8761bu_config.bin
[ 6098.394457] Bluetooth: hci0: RTL: cfg_sz 6, total sz 30210
[ 6099.142095] Bluetooth: hci0: RTL: fw version 0xdfc6d922
[ 6099.281235] Bluetooth: MGMT ver 1.22

3. hciconfig -a 命令输出 #

hci0:   Type: Primary  Bus: USB
BD Address: 0A:62:29:01:34:0D  ACL MTU: 1021:6  SCO MTU: 255:12
UP RUNNING PSCAN ISCAN INQUIRY
RX bytes:7835 acl:0 sco:0 events:230 errors:0
TX bytes:35742 acl:0 sco:0 commands:205 errors:0
Features: 0xff 0xff 0xff 0xfe 0xdb 0xfd 0x7b 0x87
Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV2 HV3
Link policy: RSWITCH HOLD SNIFF PARK
Link mode: PERIPHERAL ACCEPT
Name: 'evgeny-ubuntu'
Class: 0x7c0104
Service Classes: Rendering, Capturing, Object Transfer, Audio, Telephony
Device Class: Computer, Desktop workstation
HCI Version: 5.1 (0xa)  Revision: 0xdfc6
LMP Version: 5.1 (0xa)  Subversion: 0xd922
Manufacturer: Realtek Semiconductor Corporation (93)

无法工作的Ugreen CM749（蓝牙5.4）相关输出 #

1. lsusb 命令输出 #

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 c0f4:05e0 SZH usb keyboard
Bus 001 Device 005: ID 33fa:0010  USB2.0-BT
Bus 001 Device 004: ID 09da:c10a A4Tech Co., Ltd. USB Mouse
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

2. sudo dmesg|egrep -i 'blue|firm' 命令输出 #

[    0.141167] Spectre V2 : Enabling Speculation Barrier for firmware calls
[    0.346768] ACPI: [Firmware Bug]: BIOS _OSI(Linux) query ignored
[    0.409321] acpi PNP0A08:00: [Firmware Info]: MMCONFIG for domain 0000 [bus 00-3f] only partially covers this bridge
[    1.676838] usb 1-3: Product: Bluetooth Radio
[    4.225739] Bluetooth: Core ver 2.22
[    4.225763] NET: Registered PF_BLUETOOTH protocol family
[    4.225765] Bluetooth: HCI device and connection manager initialized
[    4.225770] Bluetooth: HCI socket layer initialized
[    4.225774] Bluetooth: L2CAP socket layer initialized
[    4.225779] Bluetooth: SCO socket layer initialized
[    4.390769] Bluetooth: hci0: RTL: examining hci_ver=0a hci_rev=000b lmp_ver=0a lmp_subver=8761
[    4.393774] Bluetooth: hci0: RTL: rom_version status=0 version=1
[    4.393781] Bluetooth: hci0: RTL: loading rtl_bt/rtl8761bu_fw.bin
[    4.415884] Bluetooth: hci0: RTL: loading rtl_bt/rtl8761bu_config.bin
[    4.419289] Bluetooth: hci0: RTL: cfg_sz 6, total sz 30210
[    5.166834] Bluetooth: hci0: RTL: fw version 0xdfc6d922
[    6.853668] [drm] Found UVD firmware Version: 1.130 Family ID: 16
[    6.856060] [drm] Found VCE firmware Version: 53.26 Binary ID: 3
[    7.174650] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[    7.174655] Bluetooth: BNEP filters: protocol multicast
[    7.174661] Bluetooth: BNEP socket layer initialized
[    7.177395] Bluetooth: MGMT ver 1.22
[   56.970179] Bluetooth: RFCOMM TTY layer initialized
[   56.970187] Bluetooth: RFCOMM socket layer initialized
[   56.970193] Bluetooth: RFCOMM ver 1.11
[ 5345.185364] Bluetooth: hci0: Opcode 0x1005 failed: -110
[ 5345.185365] Bluetooth: hci0: command 0x1005 tx timeout

3. hciconfig -a 命令输出 #

hci0:   Type: Primary  Bus: USB
BD Address: 00:A7:41:03:04:51  ACL MTU: 0:0  SCO MTU: 0:0
DOWN
RX bytes:165 acl:0 sco:0 events:9 errors:0
TX bytes:273 acl:0 sco:0 commands:10 errors:0
Features: 0xbf 0xee 0x49 0xfa 0xdb 0xbf 0x7b 0x87
Packet type: DM1 DM3 DM5 DH1 DH3 DH5 HV1 HV3
Link policy:
Link mode: PERIPHERAL ACCEPT

我注意到一个关键差异：CM749的hciconfig输出显示状态为DOWN，而正常工作的CM390是UP RUNNING状态；而且从dmesg日志里也看不到系统加载CM749对应固件的记录。这个适配器在Windows 10上完全正常，说明硬件本身没有问题。

想请教各位，我需要做些什么配置或安装什么组件，才能让Ugreen CM749在Ubuntu 22.04上正常工作呢？

备注：内容来源于stack exchange，提问作者user153742