From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751441AbdCZNww (ORCPT ); Sun, 26 Mar 2017 09:52:52 -0400 Received: from mail-wr0-f193.google.com ([209.85.128.193]:36477 "EHLO mail-wr0-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751354AbdCZNwv (ORCPT ); Sun, 26 Mar 2017 09:52:51 -0400 From: Nicolai Stange To: Thomas Gleixner Cc: John Stultz , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, Dou Liyang , Gu Zheng , linux-kernel@vger.kernel.org, Nicolai Stange Subject: [PATCH] x86/apic/timer: set ->min_delta_ticks and ->max_delta_ticks Date: Sun, 26 Mar 2017 15:44:03 +0200 Message-Id: <20170326134403.16226-1-nicstange@gmail.com> X-Mailer: git-send-email 2.12.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org In preparation for making the clockevents core NTP correction aware, all clockevent device drivers must set ->min_delta_ticks and ->max_delta_ticks rather than ->min_delta_ns and ->max_delta_ns: a clockevent device's rate is going to change dynamically and thus, the ratio of ns to ticks ceases to stay invariant. Make the x86 arch's apic clockevent driver initialize these fields properly. This patch alone doesn't introduce any change in functionality as the clockevents core still looks exclusively at the (untouched) ->min_delta_ns and ->max_delta_ns. As soon as this has changed, a followup patch will purge the initialization of ->min_delta_ns and ->max_delta_ns from this driver. Signed-off-by: Nicolai Stange --- Notes: (First test sending for 23 similar patches in different subsystems to follow.) This prerequisite patch is part of a larger effort to feed NTP corrections into the clockevent devices' frequencies and thus avoiding their notion of time to diverge from the system's one. If you're interested, the current state of the whole series can be found at [1]. If you haven't got any objections and these prerequisites get merged by 4.12 everywhere, I'll proceed with the remainder of this series in 4.13. Applicable to next-20170324 as well as to John' Stultz tree [2]. [1] git://nicst.de/linux.git cev-freq-adj.v10.fortglx-4.12-time https://nicst.de/git/?p=linux.git;a=shortlog;h=refs/heads/cev-freq-adj.v10.fortglx-4.12-time [2] https://git.linaro.org/people/john.stultz/linux.git fortglx/4.12/time arch/x86/kernel/apic/apic.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c index 8ccb7ef512e0..875091d4609d 100644 --- a/arch/x86/kernel/apic/apic.c +++ b/arch/x86/kernel/apic/apic.c @@ -731,8 +731,10 @@ static int __init calibrate_APIC_clock(void) TICK_NSEC, lapic_clockevent.shift); lapic_clockevent.max_delta_ns = clockevent_delta2ns(0x7FFFFF, &lapic_clockevent); + lapic_clockevent.max_delta_ticks = 0x7FFFFF; lapic_clockevent.min_delta_ns = clockevent_delta2ns(0xF, &lapic_clockevent); + lapic_clockevent.min_delta_ticks = 0xF; lapic_clockevent.features &= ~CLOCK_EVT_FEAT_DUMMY; return 0; } @@ -778,8 +780,10 @@ static int __init calibrate_APIC_clock(void) lapic_clockevent.shift); lapic_clockevent.max_delta_ns = clockevent_delta2ns(0x7FFFFFFF, &lapic_clockevent); + lapic_clockevent.max_delta_ticks = 0x7FFFFFFF; lapic_clockevent.min_delta_ns = clockevent_delta2ns(0xF, &lapic_clockevent); + lapic_clockevent.min_delta_ticks = 0xF; lapic_timer_frequency = (delta * APIC_DIVISOR) / LAPIC_CAL_LOOPS; -- 2.12.0