From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756341Ab3CaXl6 (ORCPT ); Sun, 31 Mar 2013 19:41:58 -0400 Received: from mail-wg0-f48.google.com ([74.125.82.48]:43933 "EHLO mail-wg0-f48.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756149Ab3CaXlv (ORCPT ); Sun, 31 Mar 2013 19:41:51 -0400 Message-ID: <5158C9B8.3070208@linaro.org> Date: Mon, 01 Apr 2013 01:41:44 +0200 From: Daniel Lezcano User-Agent: Mozilla/5.0 (X11; Linux i686; rv:17.0) Gecko/20130308 Thunderbird/17.0.4 MIME-Version: 1.0 To: ning.n.jiang@gmail.com CC: linux@arm.linux.org.uk, kgene.kim@samsung.com, davidb@codeaurora.org, dwalker@fifo99.com, bryanh@codeaurora.org, john.stultz@linaro.org, tglx@linutronix.de, linus.walleij@linaro.org, shawn.guo@linaro.org, rob.herring@calxeda.com, arnd@arndb.de, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-samsung-soc@vger.kernel.org, linux-arm-msm@vger.kernel.org Subject: Re: [PATCH] ARM: timer: Shutdown clock event device when stopping local timer References: <1364549049-29278-1-git-send-email-ning.n.jiang@gmail.com> In-Reply-To: <1364549049-29278-1-git-send-email-ning.n.jiang@gmail.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 03/29/2013 10:24 AM, ning.n.jiang@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