USB devices do not enter suspended state as expected in Windows 8

Symptoms

USB devices may not always enter a suspended, low-power mode on a Windows 8-based computer as expected. For example, this may occur when the computer goes to sleep. 

This issue does not affect the functioning of the USB device, and users generally do not notice the issue. However, when you run the PowerCfg.exe tool and use the /energy option, a message that resembles the following is displayed:
USB Suspend:USB Device Rarely Entering Selective Suspend
This device intermittently entered the USB Selective Suspend state during the trace. Processor power management may be prevented when this USB device is not in the Selective Suspend state. Note that this issue will not prevent the system from sleeping.
Device Name XXX
Host Controller ID XXX
Host Controller Location PCI bus 0, device 19, function 0
Device ID XXX
Port Path 1
Time Suspended (%) 12

This issue occurs when the following conditions are true:
  • The controller sets the RootHubStatusChange event for setting remote wake-up when the controller enters into selective suspend.
  • Microsoft USB 1.0 is installed.

Status

Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.

This issue does not affect the performance of the USB device, nor does it prevent your computer from sleeping or hibernating.

More Information

According to the USB 1.0 specifications, the host controller sets the RootHubStatusChange bit when there is a change to any bits in HcRhStatus or HcRhPortStatus that include remote wake-up bits. However, if the controller does this when it enters into selective suspend, the USB driver could be mis-alerted that the controller has become active again. Therefore, the USB driver resumes the hub. There is a difference among controllers in the market about whether to remove this behavior or to strictly follow the specifications. If the controller wants to implement the behavior, this problem may occur. However, this does not affect the major function of the USB device.
Svojstva

ID članka: 2962969 - Poslednji pregled: 08.05.2014. - Verzija: 1

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