| 摘要 |
A USB bus-powered device in Suspend state that requires active bus state power levels, but has no data transfer need, may initiate Resume signaling to return a USB bus segment to active state, without transferring any data across the bus. A device driver considers both USB device power needs and data transfer activity in deciding to Globally or Selectively Suspend a bus or bus segment. In particular, upon deciding to Suspend a bonus or bus segment, the device driver queries a USB bus-powered device. If the device will require active bus mode power within a predetermined duration, the device will indicate to the device driver to remain an active mode. In this case, the device driver does not direct the USB host to Suspend the bus.
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