The Beaglebone Black can power on/off USB ports via
This can be useful for scheduled and/or remote powering off of peripherals to save energy.
git clone https://github.com/VCTLabs/devmem2 make make install
Power on USB port remotely via devmem2
devmem2 0x47401c60 b 1
This powered up my Wifi dongle.
I measured 0 Vdc on the USB host port before issuing this command, and measured 5 Vdc after the command.