From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758487Ab3K1OAK (ORCPT ); Thu, 28 Nov 2013 09:00:10 -0500 Received: from v094114.home.net.pl ([79.96.170.134]:53696 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1757373Ab3K1OAI (ORCPT ); Thu, 28 Nov 2013 09:00:08 -0500 From: "Rafael J. Wysocki" To: Viresh Kumar Cc: Dirk Brandewie , Lists linaro-kernel , Patch Tracking , "cpufreq@vger.kernel.org" , "linux-pm@vger.kernel.org" , Linux Kernel Mailing List , Nishanth Menon , Carlos Hernandez Subject: Re: [PATCH V2] cpufreq: Make sure CPU is running on a freq from freq-table Date: Thu, 28 Nov 2013 15:12:57 +0100 Message-ID: <2065797.S0ijuuXCoe@vostro.rjw.lan> User-Agent: KMail/4.10.5 (Linux/3.12.0-rc6+; KDE/4.10.5; x86_64; ; ) In-Reply-To: References: <046513da96dfec919a1a41d270c167147d4a9c8d.1385353358.git.viresh.kumar@linaro.org> <14305907.pSqK27Oikr@vostro.rjw.lan> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, November 28, 2013 07:11:17 PM Viresh Kumar wrote: > On 28 November 2013 18:39, Rafael J. Wysocki wrote: > > acpi-cpufreq is one at least. > > > > Anyway, this isn't about ACPI or anything like that, but hardware. Generally > > speaking, on modern Intel hardware the processor itself chooses the frequency > > to run at and it may do that behind your back. Moreover, it can choose a > > frequency different from the one you asked for. And it won't choose one that > > it can't run at for that matter. :-) > > > > Overall, I don't believe that the problem you're trying to address is relevant > > for any non-exotic x86 hardware. > > Okay.. So wouldn't it be better that we add this special flag only when we > face a real problem? Otherwise this flag might stay unused for long time > and then we might end up removing it.. > > >> > So there should be a flag for > >> > drivers indicating whether or not frequencies (or operation points in > >> > general) are directly testable and the check should only be done for > >> > the drivers with the flag set. > >> > >> Probably a flag with properties exactly opposite to what you mentioned, > >> so that we don't need to modify most of the drivers.. > > > > That would work too if you prefer it. > > In case we need this flag, what should we name it? > ALLOW_UNKNOWN_FREQ ?? SKIP_INITIAL_FREQUENCY_CHECK ? -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.