Bluetooth scan doesn't detect any device on Ubuntu 21.10

Question

I have just bought a Tp-link bluetooth 5.0 usb adapter (UB500), I've checked and its chip is Realtek RTL8761B. It works just fine on Windows 10, but I'm having problems on Ubuntu. I'm running Ubuntu 21.10 and I've just upgraded to the latest stable kernel version: 5.14.14. Before upgrading I tried this solution but with no success: https://linuxreviews.org/Realtek_RTL8761B

I've tried almost everything I've found online, but most of the solutions don't apply because there is no evident problem: the adapter seems to be correctly installed and properly working, however scanning does not pick up any bluetooth device. I've tried two headsets (that I know are properly working) and my phone, with no success. When performing a scan on my phone, the computer doesn't show up, even if I've set it to visible.

I can't figure out what the problem is.

    dmesg |grep -i bluetooth
    [    3.596913] Bluetooth: Core ver 2.22
    [    3.596935] NET: Registered PF_BLUETOOTH protocol family
    [    3.596936] Bluetooth: HCI device and connection manager initialized
    [    3.596939] Bluetooth: HCI socket layer initialized
    [    3.596941] Bluetooth: L2CAP socket layer initialized
    [    3.596945] Bluetooth: SCO socket layer initialized
    [   93.519895] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
    [   93.519899] Bluetooth: BNEP filters: protocol multicast
    [   93.519903] Bluetooth: BNEP socket layer initialized
    [  144.060814] Bluetooth: RFCOMM TTY layer initialized
    [  144.060821] Bluetooth: RFCOMM socket layer initialized
    [  144.060825] Bluetooth: RFCOMM ver 1.11

    hciconfig -a
    hci0:    Type: Primary  Bus: USB
        BD Address: E8:48:B8:C8:20:00  ACL MTU: 1021:6  SCO MTU: 255:12
        UP RUNNING 
        RX bytes:4264 acl:0 sco:0 events:560 errors:0
        TX bytes:9000 acl:0 sco:0 commands:490 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: SLAVE ACCEPT 
        Name: 'gaia-ubuntu-desktop'
        Class: 0x7c0104
        Service Classes: Rendering, Capturing, Object Transfer, Audio, Telephony
        Device Class: Computer, Desktop workstation
        HCI Version: 5.1 (0xa)  Revision: 0xb
        LMP Version: 5.1 (0xa)  Subversion: 0x8761
        Manufacturer: Realtek Semiconductor Corporation (93)

    rfkill list
    0: hci0: Bluetooth
        Soft blocked: no
        Hard blocked: no

    lsusb
    Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
    Bus 003 Device 004: ID 046d:0826 Logitech, Inc. HD Webcam C525
    Bus 003 Device 003: ID 04b8:013d Seiko Epson Corp. Epson Perfection V39
    Bus 003 Device 002: ID 0c76:2068 JMTek, LLC. USB MIC-SG01
    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 2357:0604 TP-Link TP%Link UB500 Adapter
    Bus 001 Device 002: ID 062a:3633 MosArt Semiconductor Corp. Full-Speed Mouse
    Bus 001 Device 004: ID 145f:0176 Trust Isla Keyboard
    Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

usb-devices | awk '/0604/' RS=
T:  Bus=01 Lev=01 Prnt=01 Port=07 Cnt=03 Dev#=  3 Spd=12  MxCh= 0
D:  Ver= 1.10 Cls=e0(wlcon) Sub=01 Prot=01 MxPS=64 #Cfgs=  1
P:  Vendor=2357 ProdID=0604 Rev=02.00
S:  Manufacturer= 
S:  Product=TP%Link UB500 Adapter
S:  SerialNumber=E848B8C82000
C:  #Ifs= 2 Cfg#= 1 Atr=e0 MxPwr=500mA
I:  If#=0x0 Alt= 0 #EPs= 3 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb
I:  If#=0x1 Alt= 0 #EPs= 2 Cls=e0(wlcon) Sub=01 Prot=01 Driver=btusb

Solution 1

I have faced the same issue with the Tp-Link UB500 adapter and I could solve this problem as suggested by Pilot6. Follow the steps below. Thanks to Pilot6.

Step 1: Download and extract Linux kernel source file.

wget https://cdn.kernel.org/pub/linux/kernel/v5.x/linux-5.11.tar.xz
tar xpvf linux-5.11.tar.xz

Be sure to use kernel version according to your system (can be checked with uname -r)

Step 2: Edit btusb.c

cd linux-5.11/drivers/bluetooth
gedit btusb.c

add the following

/* Tp-Link UB500 */
{ USB_DEVICE(0x2357, 0x0604), .driver_info = BTUSB_REALTEK },

Under the section "static const struct usb_device_id blacklist_table[]". After /* Silicon Wave based devices */.

Step 3: Edit hci_ldisc.c

(may not be needed for some versions of kernel)

Replace

static ssize_t hci_uart_tty_read(struct tty_struct *tty, struct file *file,
                 unsigned char __user *buf, size_t nr)

to

static ssize_t hci_uart_tty_read(struct tty_struct *tty, struct file *file,
                 unsigned char __user *buf, size_t nr,
                 void **cookie, unsigned long offset)

Step 4: Compile modules

make -C /lib/modules/$(uname -r)/build M=$(pwd) clean
cp /usr/src/linux-headers-$(uname -r)/.config ./
cp /usr/src/linux-headers-$(uname -r)/Module.symvers Module.symvers
make -C /lib/modules/$(uname -r)/build M=$(pwd) modules
sudo cp btusb.ko /lib/modules/$(uname -r)/kernel/drivers/bluetooth

If you have secure boot, it's also needed to sign the module, search for "How to sign things for Secure Boot".

Step 5: Repalce the old module

sudo cp btusb.ko /lib/modules/$(uname -r)/kernel/drivers/bluetooth

Step 6: Load new btusb

sudo modprobe -r btusb
sudo modprobe -v btusb

It's working for me!

Solution 2

I followed the steps in @gauthsree answer and the system stopped detecting the adapter.

Then (after a lot of searching and reading) i ran lsusb; dmesg | egrep -i 'blue|firm' and got this:

RTL: firmware file rtl_bt/rtl8761b_fw.bin not found

So, i downloaded the file and placed in: /lib/firmware/rtl_bt/

Then, reboot the system and finally works!

I followed this tutorial: Bluetooth 5.0 chipset Realtek RTL8761B to download and copy the firmware.

My system:

• OS: Ubuntu 20.04.1
• Kernel: 5.11.0-46-generic

Hope this help!

Solution 3

If the device is RTL8761B, then a patch to btusb.c kernel code is needed, adding this:

 /* Tp-Link UB500 */
{ USB_DEVICE(0x2357, 0x0604), .driver_info = BTUSB_REALTEK },

The problem is that nobody has added this device to Linux kernel yet. The chip seems to be supported, but the Tp-Link id is not there.

I suggest reporting this to Launchpad. Boot with an Ubuntu kernel and run in a terminal

ubuntu-bug linux

That will create a bug report.

Update: For Ubuntu 20.04 with the 5.15 kernel and Ubuntu 22.04+ the patch has been added to kernel source. The device should work without additional effort.

Comments

[gwendydd]

Gosh, I don't know how to do this. I've added those lines to btusb.c but I have no idea what to do after that 🤦 I will report it anyway. Thank you

[Pilot6]

After that you need to build a kernel, install it and test if BT works.

[gwendydd]

I've just never done it before

[gwendydd]

It's still not working :/

[Pilot6]

So did you build a custom kernel?

[gwendydd]

actually I'm not 100% sure what I did, but apparently it didn't work. And I mean uname -r doesn't show the kernel version I thought I was installing, but the one I had before. I'm kinda lost, I'll probably just report the bug

[Pilot6]

Please drop a link from Launchpad. Maybe I'll make a module if I have time. BTW, you can build only btusb module.

[gwendydd]

here it is, lousy as it is, since ubuntu-bug doesn't seem to work 🤦 bugs.launchpad.net/ubuntu/+source/linux/+bug/1948502 btw thank you for your time

[gwendydd]

Thank you so much! Just a question: at what point of btusb.c should I add those lines? just to make sure I don't make further mistakes 😅

[gauthsree]

I have added under the section "static const struct usb_device_id blacklist_table[]". After /* Silicon Wave based devices */.

[gwendydd]

omg IT WORKED! Thank you so much!

[Pilot6]

Can you explain void **cookie, unsigned long offset? It looks like a "dirty hack to me". We need to upstream a patch if we want it in Linux.

[Pilot6]

As a temporary solution it makes sense to create a dkms btusb module to have it working with kernel updates. It is quite easy.

[Asifa.K]

Hrm, doesn't seem to work for me on Ubuntu 21.04.

[Guillaume Husta]

It seems a similar patch has been submitted there : spinics.net/lists/linux-bluetooth/msg94476.html

[Guillaume Husta]

...which should land in linux kernel 5.16 according to : bbs.archlinux.org/viewtopic.php?pid=2003276#p2003276

[Anderson]

I think this does not work on Ubuntu 20.04

[Thomas Kimber]

How soon is this likely to be resolved in an upcoming Ubuntu patch?

[Ash]

this didn't resolve my issue, but its not every day you learn how to patch a kernel - thank you this is awesome!

[SRG]

Thank you so much, Laion! This was the last step missing from @gauthsree's answer. I also needed to authenticate my keyboard and followed this guide to solve the issue: itectec.com/ubuntu/…

[Alexander Soare]

Lifesaver! This worked for me on Ubuntu 20.04

[We are Borg]

Not working, getting /hci_vhci.c:181:7: error: ‘HCI_ISODATA_PKT’ undeclared while compiling.

[Pilot6]

It is unclear what is this post about? Does it answer the question? Or it is some fix for KDE Neon, which is off-topic here?

[Max Christian Potaß]

A script that does all the steps of Aeolun. So a general fix for ubuntu. Which does not work for me anymore.

[Pilot6]

Why post it if it doesn't work?

[Max Christian Potaß]

It does do, what Aeolun posted as a possible fix. The fix did work for me on Kubuntu. It does not work for me on KDE Neon, however. So It might help, it might not help. I don't know. But if you want to try, you can use the script, which makes it easier. I am not sure, what is unclear about that.

[Max Christian Potaß]

I did change the part below the script. Maybe it was that?

[Max Christian Potaß]

@Pilot6 Check again. I updated my script. It fixes it now completely.

[J. Knoblauch]

This may be silly, but make sure that you do step 4 while in the drivers/bluetooth directory of the source code rather than the top-level directory, otherwise you get errors. With that in mind, this worked for Ubuntu 20.04. I also reinstalled the firmware according to @Laion's answer.

[Admin]

only step 4 needed in the drivers/bluetoth directory? I receive errors ... should I've done step 1 , 2, 3, although there? (Ubunutu 20.04)