K 10
svn:author
V 3
sam
K 8
svn:date
V 27
2008-03-20T16:19:25.000000Z
K 7
svn:log
V 473
Workaround design botch in usb: blindly mixing bus_dma with PIO does not
work on architectures with a write-back cache as the PIO writes end up
in the cache which the sync(BUS_DMASYNC_POSTREAD) in usb_transfer_complete
then discards; compensate in the xfer methods that do PIO by pushing the
writes out of the cache before usb_transfer_complete is called.

This fixes USB on xscale and likely other places.

Sponsored by:	hobnob
Reviewed by:	cognet, imp
MFC after:	1 month

END