svn commit: r196496 - head/sys/dev/usb

[Alfred Perlstein]

Author: alfred
Date: Mon Aug 24 05:03:30 2009
New Revision: 196496
URL: http://svn.freebsd.org/changeset/base/196496

Log:
  Add a reminder comment to optimize bus_dmamap_sync calls.
  
  Submitted by:	hps

Modified:
  head/sys/dev/usb/usb_busdma.c

Modified: head/sys/dev/usb/usb_busdma.c
==============================================================================
--- head/sys/dev/usb/usb_busdma.c	Mon Aug 24 05:02:36 2009	(r196495)
+++ head/sys/dev/usb/usb_busdma.c	Mon Aug 24 05:03:30 2009	(r196496)
@@ -679,6 +679,12 @@ usb_pc_cpu_invalidate(struct usb_page_ca
 		/* nothing has been loaded into this page cache! */
 		return;
 	}
+
+	/*
+	 * TODO: We currently do XXX_POSTREAD and XXX_PREREAD at the
+	 * same time, but in the future we should try to isolate the
+	 * different cases to optimise the code. --HPS
+	 */
 	bus_dmamap_sync(pc->tag, pc->map, BUS_DMASYNC_POSTREAD);
 	bus_dmamap_sync(pc->tag, pc->map, BUS_DMASYNC_PREREAD);
 }