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=-6.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_NEOMUTT autolearn=ham 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 86021C169C4 for ; Thu, 31 Jan 2019 09:42:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 67FC92086C for ; Thu, 31 Jan 2019 09:42:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731705AbfAaJmT (ORCPT ); Thu, 31 Jan 2019 04:42:19 -0500 Received: from foss.arm.com ([217.140.101.70]:40460 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726316AbfAaJmT (ORCPT ); Thu, 31 Jan 2019 04:42:19 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 8FE13A78; Thu, 31 Jan 2019 01:42:18 -0800 (PST) Received: from queper01-lin (queper01-lin.cambridge.arm.com [10.1.195.48]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C23023F71E; Thu, 31 Jan 2019 01:42:16 -0800 (PST) Date: Thu, 31 Jan 2019 09:42:15 +0000 From: Quentin Perret To: Matthias Kaehlcke Cc: viresh.kumar@linaro.org, sudeep.holla@arm.com, rjw@rjwysocki.net, nm@ti.com, sboyd@kernel.org, linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, dietmar.eggemann@arm.com Subject: Re: [PATCH v2 1/5] PM / OPP: Introduce a power estimation helper Message-ID: <20190131094212.rjel77xcfvqj6tkr@queper01-lin> References: <20190130170506.20450-1-quentin.perret@arm.com> <20190130170506.20450-2-quentin.perret@arm.com> <20190130190703.GM81583@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190130190703.GM81583@google.com> User-Agent: NeoMutt/20171215 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Matthias, On Wednesday 30 Jan 2019 at 11:07:03 (-0800), Matthias Kaehlcke wrote: > > diff --git a/drivers/opp/of.c b/drivers/opp/of.c > > index 06f0f632ec47..4c8bf172e9ed 100644 > > --- a/drivers/opp/of.c > > +++ b/drivers/opp/of.c > > @@ -20,6 +20,7 @@ > > #include > > #include > > #include > > +#include > > nit: AFAIK typically alphabetical order is used for includes, though > this file doesn't exactly adhere to it. Yeah that's what I was thinking too. Since nothing is in order here I figured there wasn't a best place to put it so I just stick it there. I happy to re-order all of them if necessary. > > > #include "opp.h" > > > > @@ -1047,3 +1048,90 @@ struct device_node *dev_pm_opp_get_of_node(struct dev_pm_opp *opp) > > return of_node_get(opp->np); > > } > > EXPORT_SYMBOL_GPL(dev_pm_opp_get_of_node); > > + > > +/* > > + * Callback function provided to the Energy Model framework upon registration. > > + * This computes the power estimated by @CPU at the first OPP above @kHz (ceil), > > that's not entirely correct, it could be the OPP at @kHz. Right, I'll update that. > > > + * and updates @kHz and @mW accordingly. The power is estimated as > > + * P = C * V^2 * f with C being the CPU's capacitance and V and f respectively > > + * the voltage and frequency of the OPP. > > + * > > + * Returns -ENODEV if the CPU device cannot be found, -EINVAL if the power > > + * calculation failed because of missing parameters, 0 otherwise. > > + */ > > +static int __maybe_unused _get_cpu_power(unsigned long *mW, unsigned long *kHz, > > + int cpu) > > why __maybe_unused? To avoid compiler warnings with CONFIG_ENERGY_MODEL=n, see my other email ;-) > > +{ > > + struct device *cpu_dev; > > + struct dev_pm_opp *opp; > > + struct device_node *np; > > + unsigned long mV, Hz; > > + u32 cap; > > + u64 tmp; > > + int ret; > > + > > + cpu_dev = get_cpu_device(cpu); > > + if (!cpu_dev) > > + return -ENODEV; > > + > > + np = of_node_get(cpu_dev->of_node); > > + if (!np) > > + return -EINVAL; > > + > > + ret = of_property_read_u32(np, "dynamic-power-coefficient", &cap); > > + of_node_put(np); > > + if (ret) > > + return -EINVAL; > > + > > + Hz = *kHz * 1000; > > + opp = dev_pm_opp_find_freq_ceil(cpu_dev, &Hz); > > + if (IS_ERR(opp)) > > + return -EINVAL; > > + > > + mV = dev_pm_opp_get_voltage(opp) / 1000; > > + dev_pm_opp_put(opp); > > + if (!mV) > > + return -EINVAL; > > + > > + tmp = (u64)cap * mV * mV * (Hz / 1000000); > > + do_div(tmp, 1000000000); > > + > > + *mW = (unsigned long)tmp; > > + *kHz = Hz / 1000; > > + > > + return 0; > > +} > > + > > +/** > > + * dev_pm_opp_of_register_em() - Attempt to register an Energy Model > > + * @cpus : CPUs for which an Energy Model has to be registered > > + * @nr_opp : Number of OPPs to register in the Energy Model > > + * > > + * This checks whether the "dynamic-power-coefficient" devicetree binding has > > s/binding/property/ ? Sounds good. > > > + * been specified, and tries to register an Energy Model with it if it has. > > + */ > > +void dev_pm_opp_of_register_em(struct cpumask *cpus, int nr_opp) > > Is the nr_opp parameter really needed? The function looks up the CPU > device and hence could determine the OPP count itself with > dev_pm_opp_get_opp_count(). I see most cpufreq drivers call > dev_pm_opp_get_opp_count() anyway, so passing the count as parameter > can be considered a small optimization, not sure how relevant it is > though, since dev_pm_opp_of_register_em() isn't called frequently. Yeah, I figured since most callers of dev_pm_opp_of_register_em() already counted the OPPs, I could as well use the data instead of counting again. I mean, dev_pm_opp_get_count() has to traverse the whole list every time, so there is no point in doing that twice. Not a huge deal I guess. > > > +{ > > + struct em_data_callback em_cb = EM_DATA_CB(_get_cpu_power); > > + int ret, cpu = cpumask_first(cpus); > > + struct device *cpu_dev; > > + struct device_node *np; > > + u32 cap; > > + > > + cpu_dev = get_cpu_device(cpu); > > + if (!cpu_dev) > > + return; > > + > > + np = of_node_get(cpu_dev->of_node); > > + if (!np) > > + return; > > + > > + /* Don't register an EM without the right DT binding */ > > + ret = of_property_read_u32(np, "dynamic-power-coefficient", &cap); > > + of_node_put(np); > > + if (ret || !cap) > > + return; > > + > > + em_register_perf_domain(cpus, nr_opp, &em_cb); > > +} > > +EXPORT_SYMBOL_GPL(dev_pm_opp_of_register_em); > > diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h > > index b895f4e79868..58ae08b024bd 100644 > > --- a/include/linux/pm_opp.h > > +++ b/include/linux/pm_opp.h > > @@ -327,6 +327,7 @@ int dev_pm_opp_of_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpuma > > struct device_node *dev_pm_opp_of_get_opp_desc_node(struct device *dev); > > struct device_node *dev_pm_opp_get_of_node(struct dev_pm_opp *opp); > > int of_get_required_opp_performance_state(struct device_node *np, int index); > > +void dev_pm_opp_of_register_em(struct cpumask *cpus, int nr_opp); > > #else > > static inline int dev_pm_opp_of_add_table(struct device *dev) > > { > > @@ -365,6 +366,11 @@ static inline struct device_node *dev_pm_opp_get_of_node(struct dev_pm_opp *opp) > > { > > return NULL; > > } > > + > > +static inline void dev_pm_opp_of_register_em(struct cpumask *cpus, int nr_opp) > > +{ > > +} > > + > > static inline int of_get_required_opp_performance_state(struct device_node *np, int index) > > { > > return -ENOTSUPP; > > Tested-by: Matthias Kaehlcke Thank you very much ! Quentin