Microsoft KB Archive/813139

= Updating EHCI USB 2.0 driver may cause USB 1.1 devices to stop functioning =

Article ID: 813139

Article Last Modified on 9/7/2005

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APPLIES TO


 * Microsoft Windows XP Professional

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SYMPTOMS
If you try to update the device driver for an EHCI USB 2.0 host controller by using the Update Driver function in Device Manager, USB 1.1 devices that are attached to the controller may stop functioning.



CAUSE
To support USB 1.1 devices, a USB 2.0 host controller has one or more USB 1.1 compatible controllers that are enumerated as separate PCI functions by the operating system. The USB driver stack on Windows XP Service Pack 1 synchronizes the operation of a USB 2.0 host controller with the operation of its USB 1.1 compatible controllers. When the device driver for the USB 2.0 controller is updated by using the Device Manager, the controller is programmatically removed by the operating system before the driver is updated.

Due to the synchronization of the USB 2.0 controller and its USB 1.1 compatible controllers, the USB driver stack also removes the USB 1.1 compatible controllers when the USB 2.0 controller is removed. When the device driver update is complete, the USB 2.0 controller is restarted; however the USB 1.1 compatible controller remains disabled. Therefore, any USB 1.1 devices that are attached to the controller no longer function.



RESOLUTION
To restart the USB 1.1 compatible controllers after you update a USB 2.0 controller, you have to re-enumerate the hardware tree. To re-enumerate the hardware tree, use one of the following methods.
 * In Device Manager, on the Action menu, click Scan For Hardware Changes.
 * Restart the computer.

Note We do not recommend that you update the USB 2.0 host controller driver by using the Device Manager if you are using a USB keyboard and a mouse input device. When you update the USB 2.0 host controller driver by using the Device Manager, the keyboard and the mouse do not function, and you cannot control the system or safely restart the computer.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.

Keywords: kbprb kbusb KB813139

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