PERFORCE change 158592 for review

[Ulf Lilleengen]

http://perforce.freebsd.org/chv.cgi?CH=158592

Change 158592 by lulf at lulf_carrot on 2009/03/02 18:46:02

	- Make a comment about how it works, now that I think I understand it.

Affected files ...

.. //depot/projects/avr32/src/sys/avr32/avr32/busdma_machdep.c#4 edit

Differences ...

==== //depot/projects/avr32/src/sys/avr32/avr32/busdma_machdep.c#4 (text+ko) ====

@@ -460,7 +460,10 @@
 		void *tmpaddr = (void *)*vaddr;
 
 		if (tmpaddr) {
-			/* XXX: */
+			/*
+			 * Put it in the uncached area to make the sync
+			 * operations as cheap as possible for DMA.
+			 */
 			tmpaddr = (void *)AVR32_PHYS_TO_P2(vtophys(tmpaddr));
 			newmap->origbuffer = *vaddr;
 			newmap->allocbuffer = tmpaddr;