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=-8.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, 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 A8A30C433E1 for ; Thu, 28 May 2020 07:07:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 867C6207D3 for ; Thu, 28 May 2020 07:07:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=samsung.com header.i=@samsung.com header.b="FLAwhwlV" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726111AbgE1HHP (ORCPT ); Thu, 28 May 2020 03:07:15 -0400 Received: from mailout3.samsung.com ([203.254.224.33]:13835 "EHLO mailout3.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725819AbgE1HHP (ORCPT ); Thu, 28 May 2020 03:07:15 -0400 Received: from epcas1p2.samsung.com (unknown [182.195.41.46]) by mailout3.samsung.com (KnoxPortal) with ESMTP id 20200528070708epoutp03815f351a26f1f31ee4ed3dfc5c637351~TH2jYN2Lb2581825818epoutp03X for ; Thu, 28 May 2020 07:07:08 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 mailout3.samsung.com 20200528070708epoutp03815f351a26f1f31ee4ed3dfc5c637351~TH2jYN2Lb2581825818epoutp03X DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=samsung.com; s=mail20170921; t=1590649628; bh=CiG6BB1PuYpGEojCVeeKBD6x3ygZzpcBt7Es2xx2lZs=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=FLAwhwlV0b932esAkAupnM1SOf26Acex/zXRsWd2VV6ab9C8Wd9LhvdrRzjFeWxkD bmt36dN4dyL3EPaVUO1to4J1FDESrgY90bYV7B9LiyD51VefIbnTOYRJGF4aWO/fAN TJXkOOBUv64KRchIapA3rkRAooPOPHdf049IjwuI= Received: from epsnrtp3.localdomain (unknown [182.195.42.164]) by epcas1p1.samsung.com (KnoxPortal) with ESMTP id 20200528070707epcas1p15255cb8b7c89c47ff9de311c5eec534f~TH2ivV3km3190131901epcas1p1I; Thu, 28 May 2020 07:07:07 +0000 (GMT) Received: from epsmges1p1.samsung.com (unknown [182.195.40.153]) by epsnrtp3.localdomain (Postfix) with ESMTP id 49Xdzs416mzMqYl3; Thu, 28 May 2020 07:07:05 +0000 (GMT) Received: from epcas1p1.samsung.com ( [182.195.41.45]) by epsmges1p1.samsung.com (Symantec Messaging Gateway) with SMTP id EA.3C.04388.9136FCE5; Thu, 28 May 2020 16:07:05 +0900 (KST) Received: from epsmtrp2.samsung.com (unknown [182.195.40.14]) by epcas1p2.samsung.com (KnoxPortal) with ESMTPA id 20200528070704epcas1p28e7d1b06ef8e9c2e679542eb17941f52~TH2f6sDVO2041720417epcas1p2D; Thu, 28 May 2020 07:07:04 +0000 (GMT) Received: from epsmgms1p2.samsung.com (unknown [182.195.42.42]) by epsmtrp2.samsung.com (KnoxPortal) with ESMTP id 20200528070704epsmtrp22016e4512d7fee9b7704da54eef992e0~TH2f5neu13022430224epsmtrp2i; Thu, 28 May 2020 07:07:04 +0000 (GMT) X-AuditID: b6c32a35-c84b79e000001124-d8-5ecf63192c80 Received: from epsmtip2.samsung.com ( [182.195.34.31]) by epsmgms1p2.samsung.com (Symantec Messaging Gateway) with SMTP id 91.C2.08303.8136FCE5; Thu, 28 May 2020 16:07:04 +0900 (KST) Received: from [10.113.221.102] (unknown [10.113.221.102]) by epsmtip2.samsung.com (KnoxPortal) with ESMTPA id 20200528070704epsmtip24c47dd7d69cb0a2ddff39e51688154c3~TH2fhU0zI0117301173epsmtip2R; Thu, 28 May 2020 07:07:04 +0000 (GMT) Subject: Re: [PATCH 06/12] PM / devfreq: Add cpu based scaling support to passive_governor From: Chanwoo Choi To: "Andrew-sh.Cheng" , MyungJoo Ham , Kyungmin Park , Rob Herring , Mark Rutland , Matthias Brugger , "Rafael J . Wysocki" , Viresh Kumar , Nishanth Menon , Stephen Boyd , Liam Girdwood , Mark Brown Cc: linux-pm@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-mediatek@lists.infradead.org, linux-kernel@vger.kernel.org, srv_heupstream@mediatek.com, Sibi Sankar Organization: Samsung Electronics Message-ID: <7ad35770-9327-084a-d2ca-1646cabd0a4d@samsung.com> Date: Thu, 28 May 2020 16:17:25 +0900 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:59.0) Gecko/20100101 Thunderbird/59.0 MIME-Version: 1.0 In-Reply-To: <64b81eea-641c-811d-9830-718b28db4188@samsung.com> Content-Language: en-US Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA02TfUwbZRzH8/R614JWz5bJb426cs4loIXeSufDhPnGzEW3SKKZ8SV0l3IC oW/plek0cQxxY0S2mY0oBcFF2AtpRLBCQbGxdMFmUMAC25xsElicC25kgKI4tO2xyH/f5/d8 P/n9vs+LklCvUFplqd0tuOy8laGS5V396Xr9estwoeHr/g24u/0aieumZijcHIqQeKhyVoH/ GKuW4c7pCRJHexspHH1/FOH52hDCredHZbiyyogv7T9N4dmlIRkePPcjiT/oCynwykSHHE+c uEnijyfVuGORe0rDeZu8iIserpVxPZ5JBdfZdojifp74luK+atnHVYUDcs43flDOHfa1IW7g QreMm+98qOCu18pySwS+SHDpBLvFUVRqL85jXnjJ/KzZtMXA6tkc/Dijs/M2IY/J31Ggf67U GgvH6Pbw1vJYqYAXRSZrW67LUe4WdCUO0Z3HCM4iqzPHmSnyNrHcXpxpcdi2sgbDZlPMuLus pPbsOOX0fonebgq1oAo0UoNqUJIS6Gy4EqxTxLWa9iM4HthVg5Jj+haC7yMjlLSYR9DoHaPu ENHf/kHSRi+C+q4+QlrcRLAQvSyPuzT0GzDbd4SIa4rOgMC1Cwk6hb5EwNGGl+MAQf+K4Fal NwHcS6fB+NJ0YigVvQ2+OH0mAcjpR+CHU2cTA66jd0G4q2rVcx+E62cSbBL9JFxZ8Sf8BJ0K P800yyS9Abp/b0xMB3RDEnT4FkgpQz6cP9m8mkcD1wd8CklrYf5G32r9XTgTDlESXI3AFxhZ hY0QaD0W66CMdUiH9t4sqZwGPcufIqnxPXBj8UMybgFaBdUH1JLlYYj+MimT9Hr4/OAh6ihi PGvieNZE8KyJ4Pm/2WdI3obuF5yirVgQWSe79sI7UeLtZ5j86HhkRxDRSsTcrTJwkUI1ye8R 99qCCJQEk6J6ZuhcoVpVxO99R3A5zK5yqyAGkSl22h8R2nUWR+wn2d1m1rTZaDTibHaLiWWZ VFXz0mChmi7m3UKZIDgF1x1OpkzSVqBXkq8bL29d/ve9zBP1KQuB/Ncvmn0bN+n7X9TRy/4D pj+7W9tzT5LpaUdacpavGu2eudtdPZ+MfXebe4DUPDaqiVrmdlMj1u3DF9vqpvypQe2+TRXe YNPcqxnbFzXDb07/tfPq8w07H8z6e+Nb+ieetlYey56awwP7wy79N6caByNZjzJysYRnMwiX yP8HJ8vIKBEEAAA= X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFrrNIsWRmVeSWpSXmKPExsWy7bCSvK5E8vk4g/ZZOhbb179gtZj68Amb xfwj51gtzja9Ybf4dqWDyWLT42usFpd3zWGzuNx8kdHic+8RRoul1y8yWTS1GFvcblzBZvHm x1kmizOnL7FatO49wm7x79pGFotrC9+zWky/K2Sx8auHg7DHmnlrGD0u9/UyeeycdZfdY9Oq TjaPO9f2sHlsXlLv0XJyP4vHlqvtLB59W1Yxehy/sZ3J4/MmuQDuKC6blNSczLLUIn27BK6M 3qNX2QrWbGCsmHdkCWMD44Uuxi5GTg4JAROJyy//ANlcHEICOxglWmefZYZISEpMu3gUyOYA soUlDh8uBgkLCbxllNhyNA3EFhaIkXiztx+snE1AS2L/ixtsIHNEBO4zSyy/exXMYRZ4ziix tPkoG0R3E5PE2y2yIDa/gKLE1R+Pwa7gFbCTWLdiJVgNi4CqxInlR9lBbFGBMImdSx4zQdQI Spyc+YQFxOYUsJe4/28HWD2zgLrEn3mXmCFscYlbT+YzQdjyEtvfzmGewCg8C0n7LCQts5C0 zELSsoCRZRWjZGpBcW56brFhgVFearlecWJucWleul5yfu4mRnD8a2ntYNyz6oPeIUYmDsZD jBIczEoivE5nT8cJ8aYkVlalFuXHF5XmpBYfYpTmYFES5/06a2GckEB6YklqdmpqQWoRTJaJ g1OqgUmuz2bp70LdzhVinRGlHxMW/xfYlBua6X5zXcbO+do1OkzPJvy34fwje3K5wmH7E9sC k0vlNu7ZpRW42ORV8YOlgl4terUznq3YdEPkwB41nQ7xQytMd4QqnzRTE6q5eqj1he2TymPr o48J/U+O0TnatFxEJcQhtqrJWpWDjS960bX+hqN3cpwnvZ3vsSDhjEeF25ojkuGhfgfOSD5y 2//ZY8Fbhb/GVUf4bPqefkoXvfBJeXYuw8qYo/9YpWbc39KT9lqJxeH11elJyf4zS7b+nnX3 w2nNk/IP22zD5wUrrdD7UOBSJTH1+4H8he6rln9MUqpwl7gh7LjprKk4X3F/W19Da96VP12G LUXab5RYijMSDbWYi4oTAZFsXnduAwAA X-CMS-MailID: 20200528070704epcas1p28e7d1b06ef8e9c2e679542eb17941f52 X-Msg-Generator: CA Content-Type: text/plain; charset="utf-8" X-Sendblock-Type: SVC_REQ_APPROVE CMS-TYPE: 101P DLP-Filter: Pass X-CFilter-Loop: Reflected X-CMS-RootMailID: 20200520034335epcas1p45a321a1a878fb7cd7b9c9ada0a474ef7 References: <20200520034307.20435-1-andrew-sh.cheng@mediatek.com> <20200520034307.20435-7-andrew-sh.cheng@mediatek.com> <64b81eea-641c-811d-9830-718b28db4188@samsung.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Andrew-sh.Cheng, The exynos-bus.c used the passive governor. Even if don't make the problem because DEVFREQ_PARENT_DEV is zero, you need to initialize the parent_type with DEVFREQ_PARENT_DEV as following: diff --git a/drivers/devfreq/exynos-bus.c b/drivers/devfreq/exynos-bus.c index 8fa8eb541373..1c71c47bc2ac 100644 --- a/drivers/devfreq/exynos-bus.c +++ b/drivers/devfreq/exynos-bus.c @@ -369,6 +369,7 @@ static int exynos_bus_profile_init_passive(struct exynos_bus *bus, return -ENOMEM; passive_data->parent = parent_devfreq; + passive_data->parent_type = DEVFREQ_PARENT_DEV; /* Add devfreq device for exynos bus with passive governor */ bus->devfreq = devm_devfreq_add_device(dev, profile, DEVFREQ_GOV_PASSIVE, On 5/28/20 3:14 PM, Chanwoo Choi wrote: > Hi Andrew-sh.Cheng, > > Thanks for your posting. I like this approach absolutely. > I think that it is necessary. When I developed the embedded product, > I needed this feature always. > > I add the comments on below. > > > And the following email is not valid. So, I dropped this email > from Cc list. > Saravana Kannan > > > On 5/20/20 12:43 PM, Andrew-sh.Cheng wrote: >> From: Saravana Kannan >> >> Many CPU architectures have caches that can scale independent of the >> CPUs. Frequency scaling of the caches is necessary to make sure that the >> cache is not a performance bottleneck that leads to poor performance and >> power. The same idea applies for RAM/DDR. >> >> To achieve this, this patch adds support for cpu based scaling to the >> passive governor. This is accomplished by taking the current frequency >> of each CPU frequency domain and then adjust the frequency of the cache >> (or any devfreq device) based on the frequency of the CPUs. It listens >> to CPU frequency transition notifiers to keep itself up to date on the >> current CPU frequency. >> >> To decide the frequency of the device, the governor does one of the >> following: >> * Derives the optimal devfreq device opp from required-opps property of >> the parent cpu opp_table. >> >> * Scales the device frequency in proportion to the CPU frequency. So, if >> the CPUs are running at their max frequency, the device runs at its >> max frequency. If the CPUs are running at their min frequency, the >> device runs at its min frequency. It is interpolated for frequencies >> in between. >> >> Andrew-sh.Cheng change >> dev_pm_opp_xlate_opp to dev_pm_opp_xlate_required_opp devfreq->max_freq >> to devfreq->user_min_freq_req.data.freq.qos->min_freq.target_value >> for kernel-5.7 >> >> Signed-off-by: Saravana Kannan >> [Sibi: Integrated cpu-freqmap governor into passive_governor] >> Signed-off-by: Sibi Sankar >> Signed-off-by: Andrew-sh.Cheng >> --- >> drivers/devfreq/Kconfig | 2 + >> drivers/devfreq/governor_passive.c | 278 ++++++++++++++++++++++++++++++++++--- >> include/linux/devfreq.h | 40 +++++- >> 3 files changed, 299 insertions(+), 21 deletions(-) >> >> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig >> index 0b1df12e0f21..d9067950af6a 100644 >> --- a/drivers/devfreq/Kconfig >> +++ b/drivers/devfreq/Kconfig >> @@ -73,6 +73,8 @@ config DEVFREQ_GOV_PASSIVE >> device. This governor does not change the frequency by itself >> through sysfs entries. The passive governor recommends that >> devfreq device uses the OPP table to get the frequency/voltage. >> + Alternatively the governor can also be chosen to scale based on >> + the online CPUs current frequency. >> >> comment "DEVFREQ Drivers" >> >> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c >> index 2d67d6c12dce..7dcda02a5bb7 100644 >> --- a/drivers/devfreq/governor_passive.c >> +++ b/drivers/devfreq/governor_passive.c >> @@ -8,11 +8,89 @@ >> */ >> >> #include >> +#include >> +#include >> +#include >> #include >> #include >> +#include >> #include "governor.h" >> >> -static int devfreq_passive_get_target_freq(struct devfreq *devfreq, >> +static unsigned int xlate_cpufreq_to_devfreq(struct devfreq_passive_data *data, > > Need to change 'unsigned int' to 'unsigned long'. > >> + unsigned int cpu) >> +{ >> + unsigned int cpu_min, cpu_max, dev_min, dev_max, cpu_percent, max_state; > > Better to define them separately as following and then need to rename > the variable. Usually, use the 'min_freq' and 'max_freq' word for > the minimum/maximum frequency. > > unsigned int cpu_min_freq, cpu_max_freq, cpu_curr_freq, cpu_percent; > unsigned long dev_min_freq, dev_max_freq, dev_max_state, > > The devfreq used 'unsigned long'. The cpufreq used 'unsigned long' > and 'unsigned int'. You need to handle them properly. > > >> + struct devfreq_cpu_state *cpu_state = data->cpu_state[cpu]; >> + struct devfreq *devfreq = (struct devfreq *)data->this; >> + unsigned long *freq_table = devfreq->profile->freq_table; > > In this function, use 'cpu' work for cpufreq and use 'dev' for devfreq. > So, I think 'dev_freq_table' is proper name instead of 'freq_table' > for the readability. > > freq_table -> dev_freq_table > >> + struct dev_pm_opp *opp = NULL, *cpu_opp = NULL; > > In the get_target_freq_with_devfreq(), use 'p_opp' indicating > the OPP of parent device. For the consistency, I think that > use 'p_opp' instead of 'cpu_opp'. > >> + unsigned long cpu_freq, freq; > > Define the 'cpu_freq' on above with cpu_min_freq/cpu_max_freq definition. > cpu_freq -> cpu_curr_freq. > >> + >> + if (!cpu_state || cpu_state->first_cpu != cpu || >> + !cpu_state->opp_table || !devfreq->opp_table) >> + return 0; >> + >> + cpu_freq = cpu_state->freq * 1000; >> + cpu_opp = devfreq_recommended_opp(cpu_state->dev, &cpu_freq, 0); >> + if (IS_ERR(cpu_opp)) >> + return 0; >> + >> + opp = dev_pm_opp_xlate_required_opp(cpu_state->opp_table, >> + devfreq->opp_table, cpu_opp); >> + dev_pm_opp_put(cpu_opp); >> + >> + if (!IS_ERR(opp)) { >> + freq = dev_pm_opp_get_freq(opp); >> + dev_pm_opp_put(opp); > > Better to add the 'out' goto statement. > If you use 'goto out', you can reduce the one indentation > without 'else' statement. > > >> + } else { > > As I commented, when dev_pm_opp_xlate_required_opp() return successfully > , use 'goto out'. We can remove 'else' and then reduce the unneeded indentation. > > >> + /* Use Interpolation if required opps is not available */ >> + cpu_min = cpu_state->min_freq; >> + cpu_max = cpu_state->max_freq; >> + cpu_freq = cpu_state->freq; >> + >> + if (freq_table) { >> + /* Get minimum frequency according to sorting order */ >> + max_state = freq_table[devfreq->profile->max_state - 1]; >> + if (freq_table[0] < max_state) { >> + dev_min = freq_table[0]; >> + dev_max = max_state; >> + } else { >> + dev_min = max_state; >> + dev_max = freq_table[0]; >> + } >> + } else { >> + if (devfreq->user_max_freq_req.data.freq.qos->max_freq.target_value >> + <= devfreq->user_min_freq_req.data.freq.qos->min_freq.target_value) >> + return 0; >> + dev_min = >> + devfreq->user_min_freq_req.data.freq.qos->min_freq.target_value; >> + dev_max = >> + devfreq->user_max_freq_req.data.freq.qos->max_freq.target_value; > > I think it is not proper to access the variable of pm_qos structure directly. > Instead of direct access, you have to use the exported PM QoS function such as > - pm_qos_read_value(devfreq->dev.parent, DEV_PM_QOS_MIN_FREQUENCY); > - pm_qos_read_value(devfreq->dev.parent, DEV_PM_QOS_MAX_FREQUENCY); > >> + } >> + cpu_percent = ((cpu_freq - cpu_min) * 100) / cpu_max - cpu_min; >> + freq = dev_min + mult_frac(dev_max - dev_min, cpu_percent, 100); >> + } > > > I think that you better to add 'out' jump label as following: > > out: > >> + >> + return freq; >> +} >> + >> +static int get_target_freq_with_cpufreq(struct devfreq *devfreq, >> + unsigned long *freq) >> +{ >> + struct devfreq_passive_data *p_data = >> + (struct devfreq_passive_data *)devfreq->data; >> + unsigned int cpu, target_freq = 0; > > Need to define 'target_freq' with 'unsigned long' type. > >> + >> + for_each_online_cpu(cpu) >> + target_freq = max(target_freq, >> + xlate_cpufreq_to_devfreq(p_data, cpu)); >> + >> + *freq = target_freq; >> + >> + return 0; >> +} >> + >> +static int get_target_freq_with_devfreq(struct devfreq *devfreq, >> unsigned long *freq) >> { >> struct devfreq_passive_data *p_data >> @@ -23,16 +101,6 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq, >> int i, count, ret = 0; >> >> /* >> - * If the devfreq device with passive governor has the specific method >> - * to determine the next frequency, should use the get_target_freq() >> - * of struct devfreq_passive_data. >> - */ >> - if (p_data->get_target_freq) { >> - ret = p_data->get_target_freq(devfreq, freq); >> - goto out; >> - } >> - >> - /* >> * If the parent and passive devfreq device uses the OPP table, >> * get the next frequency by using the OPP table. >> */ >> @@ -102,6 +170,37 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq, >> return ret; >> } >> >> +static int devfreq_passive_get_target_freq(struct devfreq *devfreq, >> + unsigned long *freq) >> +{ >> + struct devfreq_passive_data *p_data = >> + (struct devfreq_passive_data *)devfreq->data; >> + int ret; >> + >> + /* >> + * If the devfreq device with passive governor has the specific method >> + * to determine the next frequency, should use the get_target_freq() >> + * of struct devfreq_passive_data. >> + */ >> + if (p_data->get_target_freq) >> + return p_data->get_target_freq(devfreq, freq); >> + >> + switch (p_data->parent_type) { >> + case DEVFREQ_PARENT_DEV: >> + ret = get_target_freq_with_devfreq(devfreq, freq); >> + break; >> + case CPUFREQ_PARENT_DEV: >> + ret = get_target_freq_with_cpufreq(devfreq, freq); >> + break; >> + default: >> + ret = -EINVAL; >> + dev_err(&devfreq->dev, "Invalid parent type\n"); >> + break; >> + } >> + >> + return ret; >> +} >> + >> static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq) >> { >> int ret; >> @@ -156,6 +255,140 @@ static int devfreq_passive_notifier_call(struct notifier_block *nb, >> return NOTIFY_DONE; >> } >> >> +static int cpufreq_passive_notifier_call(struct notifier_block *nb, >> + unsigned long event, void *ptr) >> +{ >> + struct devfreq_passive_data *data = >> + container_of(nb, struct devfreq_passive_data, nb); >> + struct devfreq *devfreq = (struct devfreq *)data->this; >> + struct devfreq_cpu_state *cpu_state; >> + struct cpufreq_freqs *freq = ptr; > > How about changing 'freq' to 'cpu_freqs'? > > In the drivers/cpufreq/cpufreq.c, use 'freqs' name indicating > the instance of 'struct cpufreq_freqs'. And in order to > identfy, how about adding 'cpu_' prefix for variable name? > >> + unsigned int current_freq; > > Need to define curr_freq with 'unsigned long' type > and better to use 'curr_freq' variable name. > >> + int ret; >> + >> + if (event != CPUFREQ_POSTCHANGE || !freq || >> + !data->cpu_state[freq->policy->cpu]) >> + return 0; >> + >> + cpu_state = data->cpu_state[freq->policy->cpu]; >> + if (cpu_state->freq == freq->new) >> + return 0; >> + >> + /* Backup current freq and pre-update cpu state freq*/ >> + current_freq = cpu_state->freq; >> + cpu_state->freq = freq->new; >> + >> + mutex_lock(&devfreq->lock); >> + ret = update_devfreq(devfreq); >> + mutex_unlock(&devfreq->lock); >> + if (ret) { >> + cpu_state->freq = current_freq; >> + dev_err(&devfreq->dev, "Couldn't update the frequency.\n"); >> + return ret; >> + } >> + >> + return 0; >> +} >> + >> +static int cpufreq_passive_register(struct devfreq_passive_data **p_data) >> +{ >> + struct devfreq_passive_data *data = *p_data; >> + struct devfreq *devfreq = (struct devfreq *)data->this; >> + struct device *dev = devfreq->dev.parent; >> + struct opp_table *opp_table = NULL; >> + struct devfreq_cpu_state *state; > > For the readability, I thinkt 'cpu_state' is proper instead of 'state'. > >> + struct cpufreq_policy *policy; >> + struct device *cpu_dev; >> + unsigned int cpu; >> + int ret; >> + >> + get_online_cpus(); > > Add blank line. > >> + data->nb.notifier_call = cpufreq_passive_notifier_call; >> + ret = cpufreq_register_notifier(&data->nb, >> + CPUFREQ_TRANSITION_NOTIFIER); >> + if (ret) { >> + dev_err(dev, "Couldn't register cpufreq notifier.\n"); >> + data->nb.notifier_call = NULL; >> + goto out; >> + } >> + >> + /* Populate devfreq_cpu_state */ >> + for_each_online_cpu(cpu) { >> + if (data->cpu_state[cpu]) >> + continue; >> + >> + policy = cpufreq_cpu_get(cpu); > > cpufreq_cpu_get() might return 'NULL'. I think you need to handle > return value as following: > > if (!policy) { > ret = -EINVAL; > goto out; > } else if (PTR_ERR(policy) == -EPROBE_DEFER) { > goto out; > } else if (IS_ERR(policy) { > ret = PTR_ERR(policy); > dev_err(dev, "Couldn't get the cpufreq_poliy.\n"); > goto out; > } > > If cpufreq_cpu_get() return successfully, to do next. > It reduces the one indentaion. > > > >> + if (policy) { >> + state = kzalloc(sizeof(*state), GFP_KERNEL); >> + if (!state) { >> + ret = -ENOMEM; >> + goto out; >> + } >> + >> + cpu_dev = get_cpu_device(cpu); >> + if (!cpu_dev) { >> + dev_err(dev, "Couldn't get cpu device.\n"); >> + ret = -ENODEV; >> + goto out; >> + } >> + >> + opp_table = dev_pm_opp_get_opp_table(cpu_dev); >> + if (IS_ERR(devfreq->opp_table)) { >> + ret = PTR_ERR(opp_table); >> + goto out; >> + } >> + >> + state->dev = cpu_dev; >> + state->opp_table = opp_table; >> + state->first_cpu = cpumask_first(policy->related_cpus); >> + state->freq = policy->cur; >> + state->min_freq = policy->cpuinfo.min_freq; >> + state->max_freq = policy->cpuinfo.max_freq; >> + data->cpu_state[cpu] = state; > > Add blank line. > >> + cpufreq_cpu_put(policy); >> + } else { >> + ret = -EPROBE_DEFER; >> + goto out; >> + } >> + } > > Add blank line. > >> +out: >> + put_online_cpus(); >> + if (ret) >> + return ret; >> + >> + /* Update devfreq */ >> + mutex_lock(&devfreq->lock); >> + ret = update_devfreq(devfreq); >> + mutex_unlock(&devfreq->lock); >> + if (ret) >> + dev_err(dev, "Couldn't update the frequency.\n"); >> + >> + return ret; >> +} >> + >> +static int cpufreq_passive_unregister(struct devfreq_passive_data **p_data) >> +{ >> + struct devfreq_passive_data *data = *p_data; >> + struct devfreq_cpu_state *cpu_state; >> + int cpu; >> + >> + if (data->nb.notifier_call) >> + cpufreq_unregister_notifier(&data->nb, >> + CPUFREQ_TRANSITION_NOTIFIER); >> + >> + for_each_possible_cpu(cpu) { >> + cpu_state = data->cpu_state[cpu]; >> + if (cpu_state) { >> + if (cpu_state->opp_table) >> + dev_pm_opp_put_opp_table(cpu_state->opp_table); >> + kfree(cpu_state); >> + cpu_state = NULL; >> + } >> + } >> + >> + return 0; >> +} >> + >> static int devfreq_passive_event_handler(struct devfreq *devfreq, >> unsigned int event, void *data) >> { >> @@ -165,7 +398,7 @@ static int devfreq_passive_event_handler(struct devfreq *devfreq, >> struct notifier_block *nb = &p_data->nb; >> int ret = 0; >> >> - if (!parent) >> + if (p_data->parent_type == DEVFREQ_PARENT_DEV && !parent) >> return -EPROBE_DEFER; > > If you modify the devfreq_passive_event_handler() as following, > you can move this condition for DEVFREQ_PARENT_DEV into > (register|unregister)_parent_dev_notifier. > > switch (event) { > case DEVFREQ_GOV_START: > ret = register_parent_dev_notifier(p_data); > break; > case DEVFREQ_GOV_STOP: > ret = unregister_parent_dev_notifier(p_data); > break; > default: > ret = -EINVAL; > break; > } > > return ret; > >> >> switch (event) { >> @@ -173,13 +406,24 @@ static int devfreq_passive_event_handler(struct devfreq *devfreq, >> if (!p_data->this) >> p_data->this = devfreq; >> >> - nb->notifier_call = devfreq_passive_notifier_call; >> - ret = devfreq_register_notifier(parent, nb, >> - DEVFREQ_TRANSITION_NOTIFIER); >> + if (p_data->parent_type == DEVFREQ_PARENT_DEV) { >> + nb->notifier_call = devfreq_passive_notifier_call; >> + ret = devfreq_register_notifier(parent, nb, >> + DEVFREQ_TRANSITION_NOTIFIER); >> + } else if (p_data->parent_type == CPUFREQ_PARENT_DEV) { >> + ret = cpufreq_passive_register(&p_data); > > I think that we better to collect the code related to notifier registration > into one function like devfreq_pass_register_notifier() instead of > cpufreq_passive_register() as following: I think it is more simple and readable. > > If you have more proper function name of register_parent_dev_notifier, > please give your opinion. > > > int register_parent_dev_notifier(struct devfreq_passive_data **p_data) > switch (p_data->parent_type) { > case DEVFREQ_PARENT_DEV: > nb->notifier_call = devfreq_passive_notifier_call; > ret = devfreq_register_notifier(parent, nb, > break; > case CPUFREQ_PARENT_DEV: > cpufreq_register_notifier(...) > ... > break; > } > > >> + } else { >> + ret = -EINVAL; >> + } >> break; >> case DEVFREQ_GOV_STOP: >> - WARN_ON(devfreq_unregister_notifier(parent, nb, >> - DEVFREQ_TRANSITION_NOTIFIER)); >> + if (p_data->parent_type == DEVFREQ_PARENT_DEV) >> + WARN_ON(devfreq_unregister_notifier(parent, nb, >> + DEVFREQ_TRANSITION_NOTIFIER)); >> + else if (p_data->parent_type == CPUFREQ_PARENT_DEV) >> + cpufreq_passive_unregister(&p_data); >> + else >> + ret = -EINVAL; > > ditto. unregister_parent_dev_notifier(struct devfreq_passive_data **p_data) > >> break; >> default: >> break; >> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h >> index a4b19d593151..04ce576fd6f1 100644 >> --- a/include/linux/devfreq.h >> +++ b/include/linux/devfreq.h >> @@ -278,6 +278,32 @@ struct devfreq_simple_ondemand_data { >> >> #if IS_ENABLED(CONFIG_DEVFREQ_GOV_PASSIVE) >> /** >> + * struct devfreq_cpu_state - holds the per-cpu state >> + * @freq: the current frequency of the cpu. >> + * @min_freq: the min frequency of the cpu. >> + * @max_freq: the max frequency of the cpu. >> + * @first_cpu: the cpumask of the first cpu of a policy. >> + * @dev: reference to cpu device. >> + * @opp_table: reference to cpu opp table. >> + * >> + * This structure stores the required cpu_state of a cpu. >> + * This is auto-populated by the governor. >> + */ >> +struct devfreq_cpu_state {> + unsigned int freq; > > It is better to change from 'freq' to 'curr_freq' > for more correct expression. > >> + unsigned int min_freq; >> + unsigned int max_freq; >> + unsigned int first_cpu; >> + struct device *dev; > > How about changing the name 'dev' to 'cpu_dev'? > > >> + struct opp_table *opp_table; >> +}; > > devfreq_cpu_state is only handled by within driver/devfreq/governor_passive.c. > > So, you can move it into drivers/devfreq/governor_passive.c > and just add the definition into include/linux/devfreq.h as following: > It is able to prevent the access of variable of 'struct devfreq_cpu_state' > outside. > > struct devfreq_cpu_state; > >> + >> +enum devfreq_parent_dev_type { >> + DEVFREQ_PARENT_DEV, >> + CPUFREQ_PARENT_DEV, >> +}; >> + >> +/** >> * struct devfreq_passive_data - ``void *data`` fed to struct devfreq >> * and devfreq_add_device >> * @parent: the devfreq instance of parent device. >> @@ -288,13 +314,15 @@ struct devfreq_simple_ondemand_data { >> * using governors except for passive governor. >> * If the devfreq device has the specific method to decide >> * the next frequency, should use this callback. >> - * @this: the devfreq instance of own device. >> - * @nb: the notifier block for DEVFREQ_TRANSITION_NOTIFIER list >> + * @parent_type parent type of the device > > Need to add ':' at the end of word. -> "parent_type:". > >> + * @this: the devfreq instance of own device. >> + * @nb: the notifier block for DEVFREQ_TRANSITION_NOTIFIER list > > I knew that you make them with same indentation. > But, actually, it is not related to this patch like clean-up code. > Even if it is not pretty, you better to don't touch 'this' and 'nb' indentaion. > >> + * @cpu_state: the state min/max/current frequency of all online cpu's >> * >> * The devfreq_passive_data have to set the devfreq instance of parent >> * device with governors except for the passive governor. But, don't need to >> - * initialize the 'this' and 'nb' field because the devfreq core will handle >> - * them. >> + * initialize the 'this', 'nb' and 'cpu_state' field because the devfreq core >> + * will handle them. >> */ >> struct devfreq_passive_data { >> /* Should set the devfreq instance of parent device */ >> @@ -303,9 +331,13 @@ struct devfreq_passive_data { >> /* Optional callback to decide the next frequency of passvice device */ >> int (*get_target_freq)(struct devfreq *this, unsigned long *freq); >> >> + /* Should set the type of parent device */ >> + enum devfreq_parent_dev_type parent_type; >> + >> /* For passive governor's internal use. Don't need to set them */ >> struct devfreq *this; >> struct notifier_block nb; >> + struct devfreq_cpu_state *cpu_state[NR_CPUS]; >> }; >> #endif >> >> > > -- Best Regards, Chanwoo Choi Samsung Electronics