From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lorenzo Pieralisi Subject: Re: [PATCH 0/2] drivers: cpuidle: minor suspend-to-idle fixes Date: Fri, 27 Feb 2015 10:00:00 +0000 Message-ID: <20150227100000.GA5975@red-moon> References: <1424800730-32059-1-git-send-email-lorenzo.pieralisi@arm.com> <4425438.YlYNQyf1hp@vostro.rjw.lan> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <4425438.YlYNQyf1hp@vostro.rjw.lan> Sender: linux-kernel-owner@vger.kernel.org To: "Rafael J. Wysocki" Cc: Daniel Lezcano , "linux-pm@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Peter Zijlstra , preeti@linux.vnet.ibm.com List-Id: linux-pm@vger.kernel.org [CC'ed Preeti] On Thu, Feb 26, 2015 at 11:37:54PM +0000, Rafael J. Wysocki wrote: > Me versions of the two $subject patches follow. Thank you. I am testing them and I have run into the following issue. Starting with: 3810631 ("PM / sleep: Re-implement suspend-to-idle handling") the suspend-to-idle code path in the cpuidle_idle_call() bypasses the CPUIDLE_FLAG_TIMER_STOP code path entirely. Now, on most of the current ARM platforms, the deepest idle state loses the tick device context, therefore this means that going to idle through suspend-to-idle becomes a brute force way of nuking the tick, unless I am missing something here. I am experiencing hangs on resume from suspend-to-idle when the broadcast timer is the broadast-hrtimer (ie there is no HW broadcast timer in the platform) and the deepest idle states lose the tick device context (ie they are CPUIDLE_FLAG_TIMER_STOP), I hope Preeti can help me test this on Power, still chasing the issue. I could not reproduce the issue with a HW broadcast timer device. Platform has deepest idle states that allow CPUs shutdown where the local tick device is gone on entry, I am trying to provide you with a backtrace, I need time to debug. The question I have: is it safe to bypass the CPUIDLE_FLAG_TIMER_STOP and related broadcast mode entry/exit in the suspend-to-idle path ? I do not think it is, but I am asking. I can "force" tick freeze by initializing the enter_freeze pointer in the idle states (that's the next thing I will test), but still, for platforms where that's not possible my question above is still valid. Thanks, Lorenzo