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USB Port Remains Active for Disabled or Safely Removed USB Device
Article ID: 2401954 - View products that this article applies to.
If you have a USB device connected to a computer running Windows Vista, Windows Server 2008, Windows 7, or Windows Server 2008 R2, and you then Disable the device in Device Manager, or Safely Remove the device using the system tray icon, you may observe one of the following symptoms:
When a USB device is Disabled in Device Manager or Safely Removed using the system tray icon, a Remove Device request (PnP IRP IRP_MN_REMOVE_DEVICE) is issued to perform a "Soft Removal" of the USB device. The USB device is marked as Removed for Plug and Play purposes, although the device has not been physically disconnected yet.
In Windows XP and Windows Server 2003, when a USB device is marked as Removed, the USB hub port to which it is connected is Disabled. When the port is Disabled, no further USB traffic is sent to the device.
In Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, when a USB device is marked as Removed, the USB hub port to which it is connected is not Disabled. When the USB hub port remains Enabled after the USB device is marked as Removed, the Symptoms described above may occur.
To work around this problem, a registry value can be set to cause Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2 to revert to the Windows XP and Windows Server 2003 behavior of disabling the USB hub port to which a Soft Removed USB device is attached. This workaround can be applied on a per-device basis (for all instances of a specific device (Vendor ID, Product ID, and Revision), or globally (for all enumerated USB devices).
Important This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/322756/ )How to back up and restore the registry in Windows
Per-Device SettingTo apply the workaround for a specific device, add a REG_DWORD value named DisableOnSoftRemove that has a value of 1 to the following registry subkey:
(where vvvv is the device's Vendor ID, pppp is the device's Product ID, and rrrr is the device's Revision number).
Global SettingTo apply the workaround globally for all enumerated USB devices, add a REG_DWORD value named DisableOnSoftRemove that has a value of 1 to the following registry subkey:
Effects of NOT disabling USB port on Soft Remove
The known effects of not disabling USB port on Soft Remove (Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2 default behavior) include:
Effects of disabling USB port on Soft RemoveThere are no specific known effects of disabling USB port on Soft Removal (with the above workaround applied, and Windows XP/Server 2003 default behavior). However, since this is not the default behavior for Windows Vista, Windows Server 2008, Windows 7, and Windows Server 2008 R2, this configuration has not been tested as thoroughly as the default behavior of keeping the USB port enabled upon Soft Removal. Thus, it is possible this workaround may affect the stability of USB device enumeration and power-management operations.
Effects of Soft Removing a USB deviceThe known effects of Soft Removing a USB device (with or without the above workaround applied) include:
Methods for Soft Removing a USB deviceA USB device may be placed in a Soft Removed state by the following actions:
For more information about performing the above actions, see:
Enable or Disable a Plug and Play Device
(http://msdn.microsoft.com/en-us/library/ff550930(VS.85).aspx)(Windows Driver Kit)
(http://go.microsoft.com/fwlink/?LinkId=151500)for other considerations.
Article ID: 2401954 - Last Review: October 7, 2010 - Revision: 1.0