From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759029Ab3BGQt4 (ORCPT ); Thu, 7 Feb 2013 11:49:56 -0500 Received: from avon.wwwdotorg.org ([70.85.31.133]:40872 "EHLO avon.wwwdotorg.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758907Ab3BGQty (ORCPT ); Thu, 7 Feb 2013 11:49:54 -0500 Message-ID: <5113DB2F.9090606@wwwdotorg.org> Date: Thu, 07 Feb 2013 09:49:51 -0700 From: Stephen Warren User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130106 Thunderbird/17.0.2 MIME-Version: 1.0 To: Mark Rutland CC: "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "tglx@linutronix.de" , "nico@linaro.org" , Will Deacon , Marc Zyngier , "john.stultz@linaro.org" , Santosh Shilimkar Subject: Re: [PATCHv3 4/4] arm: Add generic timer broadcast support References: <1358183124-28461-1-git-send-email-mark.rutland@arm.com> <1358183124-28461-5-git-send-email-mark.rutland@arm.com> <5112C25F.6000508@wwwdotorg.org> <20130207100403.GD16987@e106331-lin.cambridge.arm.com> In-Reply-To: <20130207100403.GD16987@e106331-lin.cambridge.arm.com> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/07/2013 03:04 AM, Mark Rutland wrote: > Hi Stephen, > > Sorry about this; I'm to blame for the bug. > > On Wed, Feb 06, 2013 at 08:51:43PM +0000, Stephen Warren wrote: >> On 01/14/2013 10:05 AM, Mark Rutland wrote: >>> Implement timer_broadcast for the arm architecture, allowing for the use >>> of clock_event_device_drivers decoupled from the timer tick broadcast >>> mechanism. >> >> Mark, this patch is now in next-20130206 and causes a crash during boot >> on Tegra. The reason appears to be because of: >> >>> diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c >> >>> @@ -524,7 +524,6 @@ static void __cpuinit percpu_timer_setup(void) >>> struct clock_event_device *evt = &per_cpu(percpu_clockevent, cpu); >>> >>> evt->cpumask = cpumask_of(cpu); >>> - evt->broadcast = smp_timer_broadcast; >> >> After that change, evt->broadcast is never assigned, and hence is NULL. >> Yet elsewhere in kernel/time/tick-broadcast.c it's used unconditionally: >> >> static void tick_do_broadcast(struct cpumask *mask) >> ... >> if (!cpumask_empty(mask)) { >> ... >> td = &per_cpu(tick_cpu_device, cpumask_first(mask)); >> td->evtdev->broadcast(mask); >> >> Now perhaps the Tegra timer driver simply isn't being set up correctly, >> so the bug is there... But the only other place I can find where >> ->broadcast is assigned is in tick_device_uses_broadcast() which only >> does it for "non-functional" timers, which doesn't apply to Tegra's timer. >> > > The intent of 12ad100046: "clockevents: Add generic timer broadcast function" > was to setup the broadcast function both for non-functional/dummy timers and > those that stop in low-power states (CLOCK_EVT_FEAT_C3STOP). I missed the > CLOCK_EVT_FEAT_C3STOP case. > > I believe the patch below will fix this for Tegra and any other platforms where > broadcast is required in low power states. > > Stephen, could you test this for Tegra? Tested-by: Stephen Warren Thanks.