From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753477AbbDCDex (ORCPT ); Thu, 2 Apr 2015 23:34:53 -0400 Received: from mail-pd0-f182.google.com ([209.85.192.182]:36060 "EHLO mail-pd0-f182.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752842AbbDCDet (ORCPT ); Thu, 2 Apr 2015 23:34:49 -0400 From: Viresh Kumar To: Thomas Gleixner , Ingo Molnar , Peter Zijlstra Cc: linaro-kernel@lists.linaro.org, linux-kernel@vger.kernel.org, Frederic Weisbecker , Kevin Hilman , Daniel Lezcano , Preeti U Murthy , Viresh Kumar Subject: [PATCH V2 2/2] Clockevents: Stop unused clockevent devices Date: Fri, 3 Apr 2015 09:04:05 +0530 Message-Id: <5146b07be7f0bc497e0ebae036590ec2fa73e540.1428031396.git.viresh.kumar@linaro.org> X-Mailer: git-send-email 2.3.0.rc0.44.ga94655d In-Reply-To: References: In-Reply-To: References: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org To avoid getting spurious interrupts on a tickless CPU, clockevent device can now be stopped by switching to ONESHOT_STOPPED state. The natural place for handling this transition is tick_program_event(). On 'expires == KTIME_MAX', we skip programming the event and so we need to fix such call sites as well, to always call tick_program_event() irrespective of the expires value. Once the clockevent device is required again, check if it was earlier put into ONESHOT_STOPPED state. If yes, switch its state to ONESHOT before programming its event. To make sure we haven't missed any corner case, add a WARN() for the case where we try to reprogram clockevent device while we aren't configured in ONESHOT_STOPPED state. Signed-off-by: Viresh Kumar --- kernel/time/clockevents.c | 4 ++++ kernel/time/hrtimer.c | 6 ++---- kernel/time/tick-oneshot.c | 16 ++++++++++++++++ 3 files changed, 22 insertions(+), 4 deletions(-) diff --git a/kernel/time/clockevents.c b/kernel/time/clockevents.c index 49ed2ea4294c..8ff54495f60b 100644 --- a/kernel/time/clockevents.c +++ b/kernel/time/clockevents.c @@ -335,6 +335,10 @@ int clockevents_program_event(struct clock_event_device *dev, ktime_t expires, if (dev->state == CLOCK_EVT_STATE_SHUTDOWN) return 0; + /* We must be in ONESHOT state here */ + WARN_ONCE(dev->state != CLOCK_EVT_STATE_ONESHOT, "Current state: %d\n", + dev->state); + /* Shortcut for clockevent devices that can deal with ktime. */ if (dev->features & CLOCK_EVT_FEAT_KTIME) return dev->set_next_ktime(expires, dev); diff --git a/kernel/time/hrtimer.c b/kernel/time/hrtimer.c index 721d29b99d10..d1be3eda83fa 100644 --- a/kernel/time/hrtimer.c +++ b/kernel/time/hrtimer.c @@ -543,8 +543,7 @@ hrtimer_force_reprogram(struct hrtimer_cpu_base *cpu_base, int skip_equal) if (cpu_base->hang_detected) return; - if (cpu_base->expires_next.tv64 != KTIME_MAX) - tick_program_event(cpu_base->expires_next, 1); + tick_program_event(cpu_base->expires_next, 1); } /* @@ -1308,8 +1307,7 @@ void hrtimer_interrupt(struct clock_event_device *dev) raw_spin_unlock(&cpu_base->lock); /* Reprogramming necessary ? */ - if (expires_next.tv64 == KTIME_MAX || - !tick_program_event(expires_next, 0)) { + if (!tick_program_event(expires_next, 0)) { cpu_base->hang_detected = 0; return; } diff --git a/kernel/time/tick-oneshot.c b/kernel/time/tick-oneshot.c index 67a64b1670bf..f8de75715c2f 100644 --- a/kernel/time/tick-oneshot.c +++ b/kernel/time/tick-oneshot.c @@ -28,6 +28,22 @@ int tick_program_event(ktime_t expires, int force) { struct clock_event_device *dev = __this_cpu_read(tick_cpu_device.evtdev); + if (unlikely(expires.tv64 == KTIME_MAX)) { + /* + * We don't need the clock event device any more, stop it. + */ + clockevents_set_state(dev, CLOCK_EVT_STATE_ONESHOT_STOPPED); + return 0; + } + + if (unlikely(dev->state == CLOCK_EVT_STATE_ONESHOT_STOPPED)) { + /* + * We need the clock event again, configure it in ONESHOT mode + * before using it. + */ + clockevents_set_state(dev, CLOCK_EVT_STATE_ONESHOT); + } + return clockevents_program_event(dev, expires, force); } -- 2.3.0.rc0.44.ga94655d