Based on information from the debian bug report, the kernel (ubuntu or mainline) doesn't matter. It's tied to udev rules implemented by the package "libmtp-runtime". I removed the package, and the bluetooth adapter works properly on boot.
** No longer affects: linux (Ubuntu) ** Also affects: libmtp (Ubuntu) Importance: Undecided Status: New -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/975222 Title: ath3k bluetooth adapter cannot load firmware To manage notifications about this bug go to: https://bugs.launchpad.net/libmtp/+bug/975222/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs