KMDF support for USB Isochronous Pipes

NTDEV
1

When reading the KMDF doc for USB read/write operations I only see support
for Interrupt and Bulk transfers.

The functions WdfUsbTargetPipeFormatrequestForRead() and
WdfUsbTargetPipeFormatrequestForWrite() indicate the pipe type must be
WdfUsbPipeTypeBulk or WdfUsbPipeTypeInterrupt.

There is no explicit notice that WdfUsbPipeTypeIsochronous pipes are
unsupported by any of the KMDF USB read/write functions.

So… can Isochronous transfers be performed through KMDF?

2

No explicit support, but you can allocate your own PURB and use
WdfUsbTargetPipeFormatRequestForUrb(). You will have to make sure the
PURB and the buffer in it are valid while the request is pending.

Alternatively you can format the request by calling
WdfRequestWdmFormatUsingStackLocation() and passing in an
IO_STACK_LOCATION that you formatted yourself.

d

-----Original Message-----
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Sent: Thursday, March 16, 2006 4:17 PM
To: Windows System Software Devs Interest List
Subject: [ntdev] KMDF support for USB Isochronous Pipes

When reading the KMDF doc for USB read/write operations I only see
support
for Interrupt and Bulk transfers.

The functions WdfUsbTargetPipeFormatrequestForRead() and
WdfUsbTargetPipeFormatrequestForWrite() indicate the pipe type must be
WdfUsbPipeTypeBulk or WdfUsbPipeTypeInterrupt.

There is no explicit notice that WdfUsbPipeTypeIsochronous pipes are
unsupported by any of the KMDF USB read/write functions.

So… can Isochronous transfers be performed through KMDF?

Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256

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