Comment 2 for bug 1542944

I built a test module. You can install it by running terminal commands:

wget https://launchpad.net/~hanipouspilot/+archive/ubuntu/bluetooth/+files/btusb-lp1542944-dkms_0.1_all.deb
sudo dpkg -i btusb-lp1542944-dkms_0.1_all.deb

Then power off the laptop and power it on.
If that does not work, post output of

dmesg | grep ath3k

And that can be fixed by installing new firmware from xenial by

wget http://mirrors.kernel.org/ubuntu/pool/main/l/linux-firmware/linux-firmware_1.155_all.deb
sudo dpkg -i linux-firmware_1.155_all.deb