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=-5.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=unavailable 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 88EAFC2BB1D for ; Tue, 7 Apr 2020 09:33:10 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5A82B2078C for ; Tue, 7 Apr 2020 09:33:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728128AbgDGJdJ (ORCPT ); Tue, 7 Apr 2020 05:33:09 -0400 Received: from foss.arm.com ([217.140.110.172]:54020 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726716AbgDGJdJ (ORCPT ); Tue, 7 Apr 2020 05:33:09 -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 1A29930E; Tue, 7 Apr 2020 02:33:08 -0700 (PDT) Received: from [10.37.12.4] (unknown [10.37.12.4]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id E5A483F73D; Tue, 7 Apr 2020 02:32:57 -0700 (PDT) Subject: Re: [PATCH v5 1/5] PM / EM: add devices to Energy Model To: Daniel Lezcano , linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, dri-devel@lists.freedesktop.org, linux-omap@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-imx@nxp.com Cc: Morten.Rasmussen@arm.com, Dietmar.Eggemann@arm.com, javi.merino@arm.com, cw00.choi@samsung.com, b.zolnierkie@samsung.com, rjw@rjwysocki.net, sudeep.holla@arm.com, viresh.kumar@linaro.org, nm@ti.com, sboyd@kernel.org, rui.zhang@intel.com, amit.kucheria@verdurent.com, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, rostedt@goodmis.org, qperret@google.com, bsegall@google.com, mgorman@suse.de, shawnguo@kernel.org, s.hauer@pengutronix.de, festevam@gmail.com, kernel@pengutronix.de, khilman@kernel.org, agross@kernel.org, bjorn.andersson@linaro.org, robh@kernel.org, matthias.bgg@gmail.com, steven.price@arm.com, tomeu.vizoso@collabora.com, alyssa.rosenzweig@collabora.com, airlied@linux.ie, daniel@ffwll.ch, liviu.dudau@arm.com, lorenzo.pieralisi@arm.com, patrick.bellasi@matbug.net, orjan.eide@arm.com, rdunlap@infradead.org, mka@chromium.org References: <20200318114548.19916-1-lukasz.luba@arm.com> <20200318114548.19916-2-lukasz.luba@arm.com> <09b680a5-a118-8c6e-0ae1-03ab5f10c573@linaro.org> <6b980e2a-c15c-0718-14b8-e8aa7510c832@linaro.org> <2a70b4ed-f18f-c1e6-1e8c-e4747807f276@arm.com> <4cee98ce-62a6-7448-a99c-3a1af6c87cf4@linaro.org> From: Lukasz Luba Message-ID: <6c2fcd42-5245-ff45-1852-0f2ec800517f@arm.com> Date: Tue, 7 Apr 2020 10:32:55 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <4cee98ce-62a6-7448-a99c-3a1af6c87cf4@linaro.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/6/20 10:17 PM, Daniel Lezcano wrote: > On 06/04/2020 18:07, Lukasz Luba wrote: >> >> >> On 4/6/20 3:58 PM, Daniel Lezcano wrote: >>> >>> Hi Lukasz, >>> >>> >>> On 06/04/2020 15:29, Lukasz Luba wrote: >>>> Hi Daniel, >>>> >>>> Thank you for the review. >>>> >>>> On 4/3/20 5:05 PM, Daniel Lezcano wrote: >>>>> >>>>> Hi Lukasz, >>>>> >>>>> >>>>> On 18/03/2020 12:45, Lukasz Luba wrote: >>>>>> Add support of other devices into the Energy Model framework not only >>>>>> the >>>>>> CPUs. Change the interface to be more unified which can handle other >>>>>> devices as well. >>>>> >>>>> thanks for taking care of that. Overall I like the changes in this >>>>> patch >>>>> but it hard to review in details because the patch is too big :/ >>>>> >>>>> Could you split this patch into smaller ones? >>>>> >>>>> eg. (at your convenience) >>>>> >>>>>    - One patch renaming s/cap/perf/ >>>>> >>>>>    - One patch adding a new function: >>>>> >>>>>       em_dev_register_perf_domain(struct device *dev, >>>>>                  unsigned int nr_states, >>>>>                  struct em_data_callback *cb); >>>>> >>>>>      (+ EXPORT_SYMBOL_GPL) >>>>> >>>>>       And em_register_perf_domain() using it. >>>>> >>>>>    - One converting the em_register_perf_domain() user to >>>>>      em_dev_register_perf_domain >>>>> >>>>>    - One adding the different new 'em' functions >>>>> >>>>>    - And finally one removing em_register_perf_domain(). >>>> >>>> I agree and will do the split. I could also break the dependencies >>>> for future easier merge. >>>> >>>>> >>>>> >>>>>> Acked-by: Quentin Perret >>>>>> Signed-off-by: Lukasz Luba >>>>>> --- >>>>> >>>>> [ ... ] >>>>> >>>>>>    2. Core APIs >>>>>> @@ -70,14 +72,16 @@ CONFIG_ENERGY_MODEL must be enabled to use the EM >>>>>> framework. >>>>>>    Drivers are expected to register performance domains into the EM >>>>>> framework by >>>>>>    calling the following API:: >>>>>>    -  int em_register_perf_domain(cpumask_t *span, unsigned int >>>>>> nr_states, >>>>>> -                  struct em_data_callback *cb); >>>>>> +  int em_register_perf_domain(struct device *dev, unsigned int >>>>>> nr_states, >>>>>> +        struct em_data_callback *cb, cpumask_t *cpus); >>>>> >>>>> Isn't possible to get rid of this cpumask by using >>>>> cpufreq_cpu_get() which returns the cpufreq's policy and from their get >>>>> the related cpus ? >>>> >>>> We had similar thoughts with Quentin and I've checked this. >>> >>> Yeah, I suspected you already think about that :) >>> >>>> Unfortunately, if the policy is a 'new policy' [1] it gets >>>> allocated and passed into cpufreq driver ->init(policy) [2]. >>>> Then that policy is set into per_cpu pointer for each related_cpu [3]: >>>> >>>> for_each_cpu(j, policy->related_cpus) >>>>      per_cpu(cpufreq_cpu_data, j) = policy; >>>> >>>>   Thus, any calls of functions (i.e. cpufreq_cpu_get()) which try to >>>> take this ptr before [3] won't work. >>>> >>>> We are trying to register EM from cpufreq_driver->init(policy) and the >>>> per_cpu policy is likely to be not populated at that phase. >>> >>> What is the problem of registering at the end of the cpufreq_online ? >> >> We want to enable driver developers to choose one of two options for the >> registration of Energy Model: >> 1. a simple one via dev_pm_opp_of_register_em(), which uses default >>    callback function calculating power based on: voltage, freq >>    and DT entry 'dynamic-power-coefficient' for each OPP >> 2. a more sophisticated, when driver provides callback function, which >>   will be called from EM for each OPP to ask for related power; >>   This interface could also be used by devices which relay not only >>   on one source of 'voltage', i.e. manipulate body bias or have >>   other controlling voltage for gates in the new 3D transistors. They >>   might provide custom callback function in their cpufreq driver. >>   This is used i.e. in cpufreq drivers which use firmware to get power, >>   like scmi-cpufreq.c; >> >> To meet this requirement the registration of EM is moved into cpufreq >> drivers, not in the framework i.e cpufreq_online(). If we could limit >> the support for only option 1. then we could move the registration >> call into cpufreq framework and clean the cpufreq drivers. > > I'm not sure to get your point but I think a series setting the scene by > moving the dev_pm_opp_of_register_em() to cpufreq_online() and remove > the cpumask may make sense. Some of the cpufreq drivers don't use dev_pm_opp_of_register_em() but instead em_register_perf_domain() with their em_data_callback [1]. It is because of point 2. described above. The dev_pm_opp_of_register_em won't work for them, so it's not a good candidate to cover all use cases in the framework. > > Can you send the split version of patch 1/5 as a series without the > other changes ? So we can focus on first ? Sure, I will only split patch 1/5 as you suggested and send v6. Thank you for your time and help. Regards, Lukasz [1] https://elixir.bootlin.com/linux/latest/source/drivers/cpufreq/scmi-cpufreq.c#L203