powertop fails to "enable usb suspend" - internal bluetooth

Desperately trying to improve battery life. Powertop offers a few suggestions, among them “Enable USB suspend” for a “Bluetooth by HP in use 100% of the time”. But this doesn’t seem to be working. The suggestion reappears immediately almost every time I command powertop to implement it. Doing it manually, adding “usbcore.autosuspend=1” as a boot option, elicits an error about unknown option, IIRC. I don’t use the bluetooth, can’t turn it off in BIOS. Bluetooth-related services were disabled, and the interface (pan0?) isn’t listed in ifconfig. Not sure what else to do.