From: Miroslav Lichvar Date: Fri, 9 Mar 2018 18:42:47 +0000 (-0800) Subject: timekeeping/ntp: Don't align NTP frequency adjustments to ticks X-Git-Tag: v4.19~1175^2~11 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=c2cda2a5bda9f1369c9d1ab54a20571c13cf2743;p=platform%2Fkernel%2Flinux-rpi.git timekeeping/ntp: Don't align NTP frequency adjustments to ticks When the timekeeping multiplier is changed, the NTP error is updated to correct the clock for the delay between the tick and the update of the clock. This error is corrected in later updates and the clock appears as if the frequency was changed exactly on the tick. Remove this correction to keep the point where the frequency is effectively changed at the time of the update. This removes a major source of the NTP error. Signed-off-by: Miroslav Lichvar Signed-off-by: John Stultz Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Prarit Bhargava Cc: Richard Cochran Cc: Stephen Boyd Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/1520620971-9567-2-git-send-email-john.stultz@linaro.org Signed-off-by: Ingo Molnar --- diff --git a/kernel/time/timekeeping.c b/kernel/time/timekeeping.c index cd03317..c1a0ac1 100644 --- a/kernel/time/timekeeping.c +++ b/kernel/time/timekeeping.c @@ -1860,8 +1860,6 @@ static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk, * xtime_nsec_2 = xtime_nsec_1 - offset * Which simplfies to: * xtime_nsec -= offset - * - * XXX - TODO: Doc ntp_error calculation. */ if ((mult_adj > 0) && (tk->tkr_mono.mult + mult_adj < mult_adj)) { /* NTP adjustment caused clocksource mult overflow */ @@ -1872,7 +1870,6 @@ static __always_inline void timekeeping_apply_adjustment(struct timekeeper *tk, tk->tkr_mono.mult += mult_adj; tk->xtime_interval += interval; tk->tkr_mono.xtime_nsec -= offset; - tk->ntp_error -= (interval - offset) << tk->ntp_error_shift; } /*