BPI-M1 How to make fastboot work?

hi guys

I try to use fastboot to flash my new u-boot.but found some problem, this is my step

  • enter u-boot by press space during boot
  • type fastboot in the command line and the board enter fastboot mode
  • win8.1 find a driver and install it.
  • in win8.1,command line, I type fastboot devices, but no device shows

I found the device driver in win8.1 is ADB interface, while it should be bootloader interface after google the reason. I tried some driver from google but still can not find bootloader driver.

anything wrong with my step? or how to make fastboot work? kindly thanks