From 63fb3a280061c5a1d9190015e5a074213f9d23c0 Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Fri, 11 Oct 2013 11:28:02 -0400 Subject: [PATCH] USB: NS_TO_US should round up Host controller drivers use the NS_TO_US macro to convert transaction times, which are computed in nanoseconds, to microseconds for scheduling. Periodic scheduling requires worst-case estimates, but the macro does its conversion using round-to-nearest. This patch changes it to use round-up, giving a correct worst-case value. Signed-off-by: Alan Stern Signed-off-by: Greg Kroah-Hartman --- include/linux/usb/hcd.h | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/include/linux/usb/hcd.h b/include/linux/usb/hcd.h index fc64b68..dbe3cd1 100644 --- a/include/linux/usb/hcd.h +++ b/include/linux/usb/hcd.h @@ -564,9 +564,8 @@ extern void usb_ep0_reinit(struct usb_device *); * of (7/6 * 8 * bytecount) = 9.33 * bytecount */ /* bytecount = data payload byte count */ -#define NS_TO_US(ns) ((ns + 500L) / 1000L) - /* convert & round nanoseconds to microseconds */ - +#define NS_TO_US(ns) DIV_ROUND_UP(ns, 1000L) + /* convert nanoseconds to microseconds, rounding up */ /* * Full/low speed bandwidth allocation constants/support. -- 2.7.4