How to reset bluetooth that stopped working on a Linux laptop? (after resuming from standby)

Question

Context:

• Linux kernel 5.10.x (5.18.x also)
• Thinkpad X1c (gen7) laptop

Problem:

Sometimes, when I set my system to sleep (suspend to RAM) and then resume, the bluetooth adapter is not found anymore. If I reboot, it works again.

When it works,

here is the (internal) bluetooth adapter as seen from lsusb:

# lsusb | grep 8087 
Bus 001 Device 006: ID 8087:0aaa Intel Corp. Bluetooth 9460/9560 Jefferson Peak (JfP)

And I'm able to scan, connect & use my bluetooth devices.

When it doesn't work:

• usually after a computer power suspend/resume (not systematically),
• lsusb does not display the above device anymore,
• I'm not able to scan, connect or even see my bluetooth adapter.

And kern.log says:

usb usb1-port10: Cannot enable. Maybe the USB cable is bad? 
usb usb1-port10: Cannot enable. Maybe the USB cable is bad? 
usb usb1-port10: attempt power cycle
usb 1-10: new low-speed USB device number 71 using xhci_hcd
usb 1-10: Device not responding to setup address.
usb 1-10: Device not responding to setup address.
usb 1-10: device not accepting address 71, error -71
usb 1-10: new low-speed USB device number 72 using xhci_hcd
usb 1-10: Device not responding to setup address.
usb 1-10: Device not responding to setup address.
usb 1-10: device not accepting address 72, error -71
usb usb1-port10: unable to enumerate USB device

Port 10 is the one connected to the bluetooth adapter.

What I already tried (doesn't work):

• systemctl restart bluetooth.service,
• modprobe -r btusb && modprobe btusb,
• bluetoothctl power on: says No default controller available,
• rfkill unblock bluetooth, even if it shows a bluetooth device and accepts the command.

My question

How can I make the Bluetooth work properly again without rebooting the whole computer?

Answer 1

May be overkill, but does actually work:

• resetting the whole USB "Bus" to which the bluetooth adapter is hardwired.

Solution

Get the PCI ID of Bus 1 "root hub" (don't know why the error):

# lsusb -v -s1:1 | grep iSerial
can't get device qualifier: Resource temporarily unavailable
can't get debug descriptor: Resource temporarily unavailable
  iSerial                 1 0000:00:14.0

And use it to unbind (will disconnect all related USB devices) and re-bind:

echo -n '0000:00:14.0' >| /sys/bus/pci/drivers/xhci_hcd/unbind && \
sleep 3 && \
echo -n '0000:00:14.0' >| /sys/bus/pci/drivers/xhci_hcd/bind

Beware, all my (internal & external) USB devices are connected to this hub: external mouse, external keyboard, internal webcam, internal fingerprint sensor... All will be (temporarily) disconnected in the process.

Result

After that kern.log says:

usb 1-10: new full-speed USB device number 6 using xhci_hcd
usb 1-10: New USB device found, idVendor=8087, idProduct=0aaa, bcdDevice= 0.02
usb 1-10: New USB device strings: Mfr=0, Product=0, SerialNumber=0
[...]
Bluetooth: hci0: Bootloader revision 0.1 build 42 week 52 2015
[...]
Bluetooth: hci0: Firmware loaded in 1643271 usecs
Bluetooth: hci0: Waiting for device to boot
Bluetooth: hci0: Device booted in 13788 usecs

And lsusb | grep 8087:

Bus 001 Device 006: ID 8087:0aaa Intel Corp.

And it is possible to use the bluetooth again!

Another way?

While it's better than rebooting, do you know another solution that would be less "intrusive"?