Microsoft has released updates for UEFI firmware and drivers for Surface Pro 4 and Surface Book on August 30, 2016.
- Microsoft driver update for Surface UEFI
- Microsoft driver update for Surface Integration
- Microsoft driver update for Surface Integration Service Device
And there are two other updates fixing several issues on other topics like display, storage and so on. The updates requires a reboot (wincentral writes about two reboots required to install the updates).