From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from v094114.home.net.pl (v094114.home.net.pl [79.96.170.134]) by lists.ozlabs.org (Postfix) with SMTP id 052881A0179 for ; Fri, 26 Sep 2014 09:39:00 +1000 (EST) From: "Rafael J. Wysocki" To: Viresh Kumar Subject: Re: [PATCH v3] cpufreq: powernv: Set the cpus to nominal frequency during reboot/kexec Date: Fri, 26 Sep 2014 01:52:09 +0200 Message-ID: <4913652.kENFQcqa9E@vostro.rjw.lan> In-Reply-To: References: <1410430423-1246-1-git-send-email-shilpa.bhat@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Cc: "linux-pm@vger.kernel.org" , Linux Kernel Mailing List , David Laight , Shilpasri G Bhat , Preeti U Murthy , "linuxppc-dev@lists.ozlabs.org" List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thursday, September 11, 2014 05:03:22 PM Viresh Kumar wrote: > On 11 September 2014 15:43, Shilpasri G Bhat > wrote: > > This patch ensures the cpus to kexec/reboot at nominal frequency. > > Nominal frequency is the highest cpu frequency on PowerPC at > > which the cores can run without getting throttled. > > > > If the host kernel had set the cpus to a low pstate and then it > > kexecs/reboots to a cpufreq disabled kernel it would cause the target > > kernel to perform poorly. It will also increase the boot up time of > > the target kernel. So set the cpus to high pstate, in this case to > > nominal frequency before rebooting to avoid such scenarios. > > > > The reboot notifier will set the cpus to nominal frequncy. > > > > Signed-off-by: Shilpasri G Bhat > > Suggested-by: Viresh Kumar > > Reviewed-by: Preeti U Murthy > > --- > > Changes v2->v3: > > We return EBUSY when cpufreq governor tries to change the frequency > > after rebooting is set to true. This results in console being flushed > > with error messages indicating failed attempts to change the > > frequency. So instead of returning EBUSY we return 0 to stop the > > governor from changing the frequency without alerting a failure to > > do the same on reboot, as this is not an errorneaos condition. > > Acked-by: Viresh Kumar Queued up for 3.18, thanks! -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.