From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 46E00C433E0 for ; Wed, 3 Jun 2020 10:40:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2E9632074B for ; Wed, 3 Jun 2020 10:40:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725926AbgFCKkY (ORCPT ); Wed, 3 Jun 2020 06:40:24 -0400 Received: from foss.arm.com ([217.140.110.172]:59786 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725828AbgFCKkX (ORCPT ); Wed, 3 Jun 2020 06:40:23 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 0A86331B; Wed, 3 Jun 2020 03:40:23 -0700 (PDT) Received: from bogus (unknown [10.37.12.118]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 152D53F305; Wed, 3 Jun 2020 03:40:20 -0700 (PDT) Date: Wed, 3 Jun 2020 11:40:17 +0100 From: Sudeep Holla To: Viresh Kumar Cc: Xiongfeng Wang , rjw@rjwysocki.net, guohanjun@huawei.com, ionela.voinescu@arm.com, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [Question]: about 'cpuinfo_cur_freq' shown in sysfs when the CPU is in idle state Message-ID: <20200603104017.GD7259@bogus> References: <20200603075200.hbyofgcyiwocl565@vireshk-i7> <20200603100727.GB7259@bogus> <20200603101010.alijrfmte2c6xv5c@vireshk-i7> <20200603101753.GC7259@bogus> <20200603102159.hzctwiqiukwhrpo7@vireshk-i7> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20200603102159.hzctwiqiukwhrpo7@vireshk-i7> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 03, 2020 at 03:51:59PM +0530, Viresh Kumar wrote: > On 03-06-20, 11:17, Sudeep Holla wrote: > > On Wed, Jun 03, 2020 at 03:40:10PM +0530, Viresh Kumar wrote: > > > On 03-06-20, 11:07, Sudeep Holla wrote: > > > > But I have another question. If we can detect that CPPC on some platforms > > > > rely on CPU registers(I assume FFH registers here and not system/io/... > > > > type of GAS registers), can we set dvfs_on_any_cpu(can't recall exact > > > > flag name) to false if not already done to prevent such issues. Or I am > > > > talking non-sense as it may be applicable only for _set operation and > > > > > > Yes, non-sense :) > > > > > > > Thanks for confirming 👍. > > Hehe. > > So, do you agree that we better do the read from the CPUs themselves ? > Yes if that is fine. I thought waking up the core was not a good solution in terms of power, but I have no objection for that as well as return 0 as IMO it aligns with the AMU counters when CPU is idle. -- Regards, Sudeep