From f18778a473bdcac2a4f25ac2117d46a2ebc5ffbc Mon Sep 17 00:00:00 2001
From: Andrew Thompson <thompsa@FreeBSD.org>
Date: Thu, 29 Oct 2009 23:13:02 +0000
Subject: [PATCH] MFC r196496

 Add a reminder comment to optimize bus_dmamap_sync calls.
---
 sys/dev/usb/usb_busdma.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/sys/dev/usb/usb_busdma.c b/sys/dev/usb/usb_busdma.c
index 3769102c510..177b94faceb 100644
--- a/sys/dev/usb/usb_busdma.c
+++ b/sys/dev/usb/usb_busdma.c
@@ -679,6 +679,12 @@ usb_pc_cpu_invalidate(struct usb_page_cache *pc)
 		/* 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);
 }