Usb and Power Managment

Hi all,

I am working on a Usb function driver using W.Oney framework for a Cypress
When system enters in stand-by mode I see the IRP_MN-SET_POWER IRPs which
notifies the DevPower = D3 and SysPower = Sleeping3.
Device detects the bus inactivity and enters in low power mode.
When the system returns in normal mode I receive the SysPower =
SystemWorking power IRP only and no DevPower notification is received and
resume interrupt seems to be not invoked on device.

  1. Which is the event that should trigger the DevPower = DO state transition
  2. Is it the device restart from low power ?
  3. Or is the transition to D0 state which should resume the device ?

I am a bit confused :=(
Any suggestion will be very appreciated,