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authorAaro Koskinen <Aaro.Koskinen@nokia.com>2009-03-04 10:07:41 -0800
committerTony Lindgren <tony@atomide.com>2009-03-04 10:07:41 -0800
commit80ea3bac3a47bc73efa334d0dd57099d0ff14216 (patch)
tree2312b3917a7ac97bfe59d0419122714a118cbcc3 /arch/arm/plat-omap/common.c
parent87d99d6f7ee3ec73b2b0212427b173502ec9d6cb (diff)
downloadlinux-linaro-stable-80ea3bac3a47bc73efa334d0dd57099d0ff14216.tar.gz
ARM: OMAP: sched_clock() corrected
After my OMAP3 board has been running for a while, I'm seeing weird latency traces like this: sh-1574 0d.h2 153us : do_timer (tick_do_update_jiffies64) sh-1574 0d.h2 153us : update_wall_time (do_timer) sh-1574 0d.h2 153us!: omap_32k_read (update_wall_time) sh-1574 0d.h2 1883us : update_xtime_cache (update_wall_time) sh-1574 0d.h2 1883us : clocksource_get_next (update_wall_time) sh-1574 0d.h2 1883us+: _spin_lock_irqsave (clocksource_get_next) and after a while: sh-17818 0d.h3 153us : do_timer (tick_do_update_jiffies64) sh-17818 0d.h3 153us : update_wall_time (do_timer) sh-17818 0d.h3 153us!: omap_32k_read (update_wall_time) sh-17818 0d.h3 1915us : update_xtime_cache (update_wall_time) sh-17818 0d.h3 1915us+: clocksource_get_next (update_wall_time) sh-17818 0d.h3 1945us : _spin_lock_irqsave (clocksource_get_next) Turns out that sched_clock() is using cyc2ns(), which returns NTP adjusted time. The sched_clock() frequency should not be adjusted. The patch deletes omap_32k_ticks_to_nsecs() and rewrites sched_clock() to do the conversion using the constant multiplier. Signed-off-by: Aaro Koskinen <Aaro.Koskinen@nokia.com> Signed-off-by: Tony Lindgren <tony@atomide.com>
Diffstat (limited to 'arch/arm/plat-omap/common.c')
-rw-r--r--arch/arm/plat-omap/common.c14
1 files changed, 5 insertions, 9 deletions
diff --git a/arch/arm/plat-omap/common.c b/arch/arm/plat-omap/common.c
index 0843b8882f93..6825fbb5a056 100644
--- a/arch/arm/plat-omap/common.c
+++ b/arch/arm/plat-omap/common.c
@@ -200,20 +200,16 @@ static struct clocksource clocksource_32k = {
};
/*
- * Rounds down to nearest nsec.
- */
-unsigned long long omap_32k_ticks_to_nsecs(unsigned long ticks_32k)
-{
- return cyc2ns(&clocksource_32k, ticks_32k);
-}
-
-/*
* Returns current time from boot in nsecs. It's OK for this to wrap
* around for now, as it's just a relative time stamp.
*/
unsigned long long sched_clock(void)
{
- return omap_32k_ticks_to_nsecs(omap_32k_read());
+ unsigned long long ret;
+
+ ret = (unsigned long long)omap_32k_read();
+ ret = (ret * clocksource_32k.mult_orig) >> clocksource_32k.shift;
+ return ret;
}
static int __init omap_init_clocksource_32k(void)