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=-2.2 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 8A58FC3F68F for ; Thu, 13 Feb 2020 12:59:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 61C0124685 for ; Thu, 13 Feb 2020 12:59:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729903AbgBMM7V (ORCPT ); Thu, 13 Feb 2020 07:59:21 -0500 Received: from foss.arm.com ([217.140.110.172]:46336 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729428AbgBMM7V (ORCPT ); Thu, 13 Feb 2020 07:59:21 -0500 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 B69091FB; Thu, 13 Feb 2020 04:59:20 -0800 (PST) Received: from localhost (unknown [10.1.198.52]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 580063F6CF; Thu, 13 Feb 2020 04:59:20 -0800 (PST) Date: Thu, 13 Feb 2020 12:59:18 +0000 From: Ionela Voinescu To: Valentin Schneider Cc: catalin.marinas@arm.com, will@kernel.org, mark.rutland@arm.com, maz@kernel.org, suzuki.poulose@arm.com, sudeep.holla@arm.com, lukasz.luba@arm.com, rjw@rjwysocki.net, peterz@infradead.org, mingo@redhat.com, vincent.guittot@linaro.org, viresh.kumar@linaro.org, linux-arm-kernel@lists.infradead.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org Subject: Re: [PATCH v3 5/7] cpufreq: add function to get the hardware max frequency Message-ID: <20200213125918.GA2397@arm.com> References: <20200211184542.29585-1-ionela.voinescu@arm.com> <20200211184542.29585-6-ionela.voinescu@arm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Thursday 13 Feb 2020 at 11:59:56 (+0000), Valentin Schneider wrote: > On 2/11/20 6:45 PM, Ionela Voinescu wrote: > > +/** > > + * cpufreq_get_hw_max_freq - get the max hardware frequency of the CPU > > + * @cpu: CPU number > > + * > > + * The default return value is the max_freq field of cpuinfo. > > + */ > > +__weak unsigned int cpufreq_get_hw_max_freq(unsigned int cpu) > > +{ > > + struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); > > + unsigned int ret_freq = 0; > > + > > + if (policy) { > > + ret_freq = policy->cpuinfo.max_freq; > > + cpufreq_cpu_put(policy); > > What about intel_pstate / turbo stuff? IIRC one of Giovanni's issues was that > turbo freq is not always reported as the max freq. Dunno if we can do > anything about it; at the very least maybe document the caveat? > Okay, I can add details in the description in regards to potential reasons to overwrite this function. But basically this is one of the reasons for making this a weak function. The best information we can generically get for maximum hardware frequency is cpuinfo.max_freq. But if platforms have the possibility to obtain this differently from either hardware or firmware they can overwrite this. Thanks, Ionela. > > + } > > + > > + return ret_freq; > > +} > > +EXPORT_SYMBOL(cpufreq_get_hw_max_freq); > > + > > static unsigned int __cpufreq_get(struct cpufreq_policy *policy) > > { > > if (unlikely(policy_is_inactive(policy))) >