Microsoft KB Archive/231912

= BUG: USB Bulk Bandwidth Reclamation Disabled In IRP Completion =

Article ID: 231912

Article Last Modified on 1/24/2007

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APPLIES TO


 * Microsoft Windows 98 Standard Edition, when used with:
 * Microsoft Windows 98 Standard Edition

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This article was previously published under Q231912



SYMPTOMS
Under Windows 98, bulk Universal Serial Bus (USB) transfers that are scheduled within the completion handler of a transfer for a control endpoint will only transfer one data packet per frame on UHCI controllers.



CAUSE
On the UHCI bus driver (UHCD.sys) shipped in Windows 98, USB bulk bandwidth reclamation is disabled when a USB transfer completes for a control endpoint. This means that a transfer for a bulk endpoint scheduled at this time will not be given unused bandwidth on the bus, and will transfer data one packet per frame, which means the transfer can take up to 16 times longer than it should.



RESOLUTION
The caller should schedule a DPC using KeInsertQueueDpc, and then submit the bulk transfer when the DPC's routine is called. Bulk bandwidth reclamation will be re-enabled by the time the DPC routine is called.



STATUS
This is a known problem in Windows 98. It has been fixed in Windows 98 Second Edition and Windows 2000.

Keywords: kbbug kbfix kboswin2000fix kbusb kbwdm KB231912

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