Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752613AbbFXWKt (ORCPT ); Wed, 24 Jun 2015 18:10:49 -0400 Received: from ozlabs.org ([103.22.144.67]:39667 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750941AbbFXWKm (ORCPT ); Wed, 24 Jun 2015 18:10:42 -0400 User-Agent: K-9 Mail for Android In-Reply-To: <1700583.a34yOllUuC@vostro.rjw.lan> References: <20150624064801.30680.3246.stgit@perfhull-ltc.austin.ibm.com> <1700583.a34yOllUuC@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Subject: Re: [PATCH] tick/idle/powerpc: Do not register idle states with CPUIDLE_FLAG_TIMER_STOP set in periodic mode From: Michael Ellerman Date: Thu, 25 Jun 2015 08:10:34 +1000 To: "Rafael J. Wysocki" , Preeti U Murthy CC: benh@kernel.crashing.org, daniel.lezcano@linaro.org, mark.rutland@arm.com, lorenzo.pieralisi@arm.com, linux-pm@vger.kernel.org, mpe@ellerman.id.au, will.deacon@arm.com, linux-kernel@vger.kernel.org, shreyas@linux.vnet.ibm.com, svaidy@linux.vnet.ibm.com, linuxppc-dev@lists.ozlabs.org Message-ID: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2120 Lines: 49 On 24 June 2015 23:50:40 GMT+10:00, "Rafael J. Wysocki" wrote: >On Wednesday, June 24, 2015 01:48:01 AM Preeti U Murthy wrote: >> On some archs, the local clockevent device stops in deep cpuidle >states. >> The broadcast framework is used to wakeup cpus in these idle states, >in >> which either an external clockevent device is used to send wakeup >ipis >> or the hrtimer broadcast framework kicks in in the absence of such a >> device. One cpu is nominated as the broadcast cpu and this cpu sends >> wakeup ipis to sleeping cpus at the appropriate time. This is the >> implementation in the oneshot mode of broadcast. >> >> In periodic mode of broadcast however, the presence of such cpuidle >> states results in the cpuidle driver calling tick_broadcast_enable() >> which shuts down the local clockevent devices of all the cpus and >> appoints the tick broadcast device as the clockevent device for each >of >> them. This works on those archs where the tick broadcast device is a >> real clockevent device. But on archs which depend on the hrtimer >mode >> of broadcast, the tick broadcast device hapens to be a pseudo device. >> The consequence is that the local clockevent devices of all cpus are >> shutdown and the kernel hangs at boot time in periodic mode. >> >> Let us thus not register the cpuidle states which have >> CPUIDLE_FLAG_TIMER_STOP flag set, on archs which depend on the >hrtimer >> mode of broadcast in periodic mode. This patch takes care of doing >this >> on powerpc. The cpus would not have entered into such deep cpuidle >> states in periodic mode on powerpc anyway. So there is no loss here. >> >> Signed-off-by: Preeti U Murthy > >4.2 material I suppose? Yes please, in fact it should be marked for stable too. cheers -- Sent from my Android phone with K-9 Mail. Please excuse my brevity. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/