Serious busdma bug in -current in relation to USB harware.

[Hans Petter Selasky]

Hi,

The virtual offset must be retained on bounce pages. Else the EHCI and OHCI 
will misplace the data! It has nothing to do with my new USB stack. That is 
the way the USB DMA engine works. It expects that when the end of the page is 
reached the next page begins. Moving a partially a page to the beginning of a 
page gets the USB DMA engine out of sync, and it will actually fill data into 
the remaining part of the first page, if the transfer length is greater than 
the partial page part. I've made a fix in P4 for I386. Can someone propagate 
this patch to the other platforms and have it committed to -current ASAP?

http://perforce.freebsd.org/chv.cgi?CH=152649

--HPS