Comment 0 for bug 1921915

Under later versions of the Ubuntu kernel (5.8) on the CM4 and (possibly?) some models of the Pi 400, the bluetooth controller is not activated by the pi-bluetooth package. This appears to be due to two issues:

* The mmcnr device is mistaken for a bluetooth controller. This in itself is harmless, but results in a spurious hci0 device. The existence of this device causes the btuart script to skip configuring the "real" bluetooth device (as it thinks it is already configured)

* The btuart script also attempts a match against the device-tree's model name looking for "Raspberry Pi 4" which doesn't match "Raspberry Pi Compute Module 4".

The upstream repository currently has commits for both these fixes but no release has been made yet. It is proposed to backport these patches into an -ubuntu2 version of the package in the meantime.