Comment 3 for bug 1773635

Please try this kernel
https://people.canonical.com/~khfeng/lp1773635/

Possible regression from this commit:
commit c9829dd3f00809ccf10afeb904ba5c53c3c3d6e7
Author: Takashi Iwai <email address hidden>
Date: Thu Mar 15 17:02:34 2018 +0100

    Bluetooth: btusb: Fix quirk for Atheros 1525/QCA6174

    BugLink: http://bugs.launchpad.net/bugs/1764973

    commit f44cb4b19ed40b655c2d422c9021ab2c2625adb6 upstream.

    The Atheros 1525/QCA6174 BT doesn't seem working properly on the
    recent kernels, as it tries to load a wrong firmware
    ar3k/AthrBT_0x00000200.dfu and it fails.

    This seems to have been a problem for some time, and the known
    workaround is to apply BTUSB_QCA_ROM quirk instead of BTUSB_ATH3012.