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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 78DECC4361B for ; Tue, 8 Dec 2020 11:35:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1212E22CF6 for ; Tue, 8 Dec 2020 11:35:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727839AbgLHLf1 (ORCPT ); Tue, 8 Dec 2020 06:35:27 -0500 Received: from foss.arm.com ([217.140.110.172]:47674 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726338AbgLHLf1 (ORCPT ); Tue, 8 Dec 2020 06:35:27 -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 525361FB; Tue, 8 Dec 2020 03:34:41 -0800 (PST) Received: from [10.57.1.242] (unknown [10.57.1.242]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 207623F68F; Tue, 8 Dec 2020 03:34:37 -0800 (PST) Subject: Re: [PATCH v4 3/4] scmi-cpufreq: get opp_shared_cpus from opp-v2 for EM To: Sudeep Holla , Viresh Kumar Cc: Nicola Mazzucato , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-pm@vger.kernel.org, devicetree@vger.kernel.org, rjw@rjwysocki.net, vireshk@kernel.org, robh+dt@kernel.org, sboyd@kernel.org, nm@ti.com, daniel.lezcano@linaro.org, morten.rasmussen@arm.com, chris.redpath@arm.com References: <20201202172356.10508-1-nicola.mazzucato@arm.com> <20201202172356.10508-4-nicola.mazzucato@arm.com> <20201208055053.kggxw26kxtnpneua@vireshk-i7> <0e4d3134-f9b2-31fa-b454-fb30265a80b5@arm.com> <20201208072611.ptsqupv4y2wybs6p@vireshk-i7> <20201208112008.niesjrunxq2jz3kt@bogus> From: Lukasz Luba Message-ID: <1f9daaf8-e850-7c1b-7a32-71367982beaf@arm.com> Date: Tue, 8 Dec 2020 11:34:36 +0000 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: <20201208112008.niesjrunxq2jz3kt@bogus> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org On 12/8/20 11:20 AM, Sudeep Holla wrote: > On Tue, Dec 08, 2020 at 12:56:11PM +0530, Viresh Kumar wrote: >> On 08-12-20, 07:22, Nicola Mazzucato wrote: >>> On 12/8/20 5:50 AM, Viresh Kumar wrote: >>>> On 02-12-20, 17:23, Nicola Mazzucato wrote: >>>>> nr_opp = dev_pm_opp_get_opp_count(cpu_dev); >>>>> if (nr_opp <= 0) { >>>>> - dev_dbg(cpu_dev, "OPP table is not ready, deferring probe\n"); >>>>> - ret = -EPROBE_DEFER; >>>>> - goto out_free_opp; >>>>> + ret = handle->perf_ops->device_opps_add(handle, cpu_dev); >>>>> + if (ret) { >>>>> + dev_warn(cpu_dev, "failed to add opps to the device\n"); >>>>> + goto out_free_cpumask; >>>>> + } >>>>> + >>>>> + ret = dev_pm_opp_set_sharing_cpus(cpu_dev, opp_shared_cpus); >>>>> + if (ret) { >>>>> + dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n", >>>>> + __func__, ret); >>>>> + goto out_free_cpumask; >>>>> + } >>>>> + >>>> >>>> Why do we need to call above two after calling >>>> dev_pm_opp_get_opp_count() ? >>> >>> Sorry, I am not sure to understand your question here. If there are no opps for >>> a device we want to add them to it >> >> Earlier we used to call handle->perf_ops->device_opps_add() and >> dev_pm_opp_set_sharing_cpus() before calling dev_pm_opp_get_opp_count(), why is >> the order changed now ? >> >> >> I am not sure why they would be duplicated in your case. I though >> device_opps_add() is responsible for dynamically adding the OPPs here. >> > > It is because of per-CPU vs per domain drama here. Imagine a system with > 4 CPUs which the firmware puts in individual domains while they all are > in the same perf domain and hence OPP is marked shared in DT. > > Since this probe gets called for all the cpus, we need to skip adding > OPPs for the last 3(add only for 1st one and mark others as shared). > If we attempt to add OPPs on second cpu probe, it *will* shout as duplicate > OPP as we would have already marked it as shared table with the first cpu. > Am I missing anything ? I suggested this as Nicola saw OPP duplicate > warnings when he was hacking up this patch. > >>> otherwise no need as they would be duplicated. >>>> And we don't check the return value of >>>> the below call anymore, moreover we have to call it twice now. > > Yes, that looks wrong, we need to add the check for non zero values, but .... > >>> >>> This second get_opp_count is required such that we register em with the correct >>> opp number after having added them. Without this the opp_count would not be correct. >> > > ... I have a question here. Why do you need to call > > em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, opp_shared_cpus..) > > on each CPU ? Why can't that be done once for unique opp_shared_cpus ? It just have to be called once, for one CPU from the mask. Otherwise for the next CPUs you should see error: "EM: exists for CPU%d" It can happen that this print is not seen when the get_cpu_device(cpu) failed, but that would lead to investigation why CPU devices are not there yet. Nicola: have you seen that print?