U-Boot USB not powered

Hi,

in the past, I successfully used uboot on beagle bone black to boot from a USB flash drive.
For some reason, it does not work anymore, printing the error “Port not available”.

=> usb start
starting USB…
Bus usb@47401800: Port not available.

After some investigations I could find that the USB port is not powered when I issue “usb start”.

Can anyone tell me if:

  1. there should be 5V at the USB port already before “usb start”?
  2. is there a command that needs to be run before “usb start” ?

thank you!