From mboxrd@z Thu Jan 1 00:00:00 1970 From: daniel.lezcano@linaro.org (Daniel Lezcano) Date: Mon, 01 Apr 2013 01:41:44 +0200 Subject: [PATCH] ARM: timer: Shutdown clock event device when stopping local timer In-Reply-To: <1364549049-29278-1-git-send-email-ning.n.jiang@gmail.com> References: <1364549049-29278-1-git-send-email-ning.n.jiang@gmail.com> Message-ID: <5158C9B8.3070208@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 03/29/2013 10:24 AM, ning.n.jiang at gmail.com wrote: > From: Ning Jiang > > Currently there are two problems when we try to stop local timer. > First, it calls set_mode function directly so mode state is not > updated for the clock event device. Second, it makes the device > unused instead of shutdown. > > A subtle error will happen because of it. When a cpu is plugged out > it will stop the local timer. It will call tick_nohz_idle_enter() > in idle thread afterwards. It will cancel the sched timer and try > to reprogram the next event. This is wrong since the local timer > is supposed to be stopped. > > The right way to stop the local timer is to shutdown it by calling > clockevents_set_mode(). Thus when we try to reprogram the clock > event device, it will return directly without doing anything since > the clock mode is CLOCK_EVT_MODE_SHUTDOWN. > > Signed-off-by: Ning Jiang > --- > arch/arm/kernel/smp_twd.c | 2 +- > arch/arm/mach-exynos/mct.c | 2 +- > arch/arm/mach-msm/timer.c | 2 +- > drivers/clocksource/arm_arch_timer.c | 2 +- > drivers/clocksource/time-armada-370-xp.c | 2 +- > 5 files changed, 5 insertions(+), 5 deletions(-) > > diff --git a/arch/arm/kernel/smp_twd.c b/arch/arm/kernel/smp_twd.c > index 3f25650..c1d4ab4 100644 > --- a/arch/arm/kernel/smp_twd.c > +++ b/arch/arm/kernel/smp_twd.c > @@ -92,7 +92,7 @@ static int twd_timer_ack(void) > > static void twd_timer_stop(struct clock_event_device *clk) > { > - twd_set_mode(CLOCK_EVT_MODE_UNUSED, clk); > + clockevents_set_mode(clk, CLOCK_EVT_MODE_SHUTDOWN); > disable_percpu_irq(clk->irq); Wouldn't be clockevents_shutdown more adequate here ? The next event will be also set. -- Linaro.org ? Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog