[src/trunk]: src/sys/arch/arm/cortex Don't adjust interval if we are too far ...

[matt <matt%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/6b18694f5c61
branches:  trunk
changeset: 337347:6b18694f5c61
user:      matt <matt%NetBSD.org@localhost>
date:      Sun Apr 12 17:08:25 2015 +0000

description:
Don't adjust interval if we are too far into the next tick.

diffstat:

 sys/arch/arm/cortex/gtmr.c |  15 ++++++++-------
 1 files changed, 8 insertions(+), 7 deletions(-)

diffs (37 lines):

diff -r ab881a3ad87b -r 6b18694f5c61 sys/arch/arm/cortex/gtmr.c
--- a/sys/arch/arm/cortex/gtmr.c        Sun Apr 12 17:05:03 2015 +0000
+++ b/sys/arch/arm/cortex/gtmr.c        Sun Apr 12 17:08:25 2015 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: gtmr.c,v 1.14 2015/03/27 11:12:08 skrll Exp $  */
+/*     $NetBSD: gtmr.c,v 1.15 2015/04/12 17:08:25 matt Exp $   */
 
 /*-
  * Copyright (c) 2012 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: gtmr.c,v 1.14 2015/03/27 11:12:08 skrll Exp $");
+__KERNEL_RCSID(0, "$NetBSD: gtmr.c,v 1.15 2015/04/12 17:08:25 matt Exp $");
 
 #include <sys/param.h>
 #include <sys/bus.h>
@@ -306,12 +306,13 @@
            ci->ci_data.cpu_name, delta, sc->sc_autoinc);
 
        /*
-        * If we got interrupted too soon (delta < sc->sc_autoinc) or
-        * we missed a tick (delta >= 2 * sc->sc_autoinc), don't try to
-        * adjust for jitter.
+        * If we got interrupted too soon (delta < sc->sc_autoinc)
+        * or we missed (or almost missed) a tick
+        * (delta >= 7 * sc->sc_autoinc / 4), don't try to adjust for jitter.
         */
-       delta -= sc->sc_autoinc;
-       if (delta >= sc->sc_autoinc) {
+       if (delta >= sc->sc_autoinc && delta <= 7 * sc->sc_autoinc / 4) {
+               delta -= sc->sc_autoinc;
+       } else {
                delta = 0;
        }
        armreg_cntv_tval_write(sc->sc_autoinc - delta);