The IRP_MJ_POWER request controls power management.
The power manager uses power requests to query and set power states.
I/O Status Block
Serial supports the following power requests:
Serial sends all other power requests down the device stack to be completed by a lower-level driver.
Serial is the default power policy owner for a serial device stack that uses Serial as a function driver or a lower-level filter driver.
For more information about the generic operation of these requests, see Rules for Handling Power IRPs.