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Date: Thu, 1 Apr 2021 09:16:30 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: "andrew-sh.cheng" <andrew-sh.cheng@...iatek.com>
Cc: MyungJoo Ham <myungjoo.ham@...sung.com>,
Kyungmin Park <kyungmin.park@...sung.com>,
Rob Herring <robh+dt@...nel.org>,
Mark Rutland <mark.rutland@....com>,
Matthias Brugger <matthias.bgg@...il.com>,
"Rafael J. Wysocki" <rjw@...ysocki.net>,
Viresh Kumar <viresh.kumar@...aro.org>,
Nishanth Menon <nm@...com>, Stephen Boyd <sboyd@...nel.org>,
Liam Girdwood <lgirdwood@...il.com>,
Mark Brown <broonie@...nel.org>, linux-pm@...r.kernel.org,
devicetree@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-mediatek@...ts.infradead.org, linux-kernel@...r.kernel.org,
srv_heupstream@...iatek.com, Sibi Sankar <sibis@...eaurora.org>
Subject: Re: [PATCH V8 1/8] PM / devfreq: Add cpu based scaling support to
passive_governor
On 3/31/21 10:03 PM, andrew-sh.cheng wrote:
> On Wed, 2021-03-31 at 17:35 +0900, Chanwoo Choi wrote:
>> On 3/31/21 5:27 PM, Chanwoo Choi wrote:
>>> Hi,
>>>
>>> On 3/31/21 5:03 PM, andrew-sh.cheng wrote:
>>>> On Thu, 2021-03-25 at 17:14 +0900, Chanwoo Choi wrote:
>>>>> Hi,
>>>>>
>>>>> You are missing to add these patches to linux-pm mailing list.
>>>>> Need to send them to linu-pm ML.
>>>>>
>>>>> Also, before received this series, I tried to clean-up these patches
>>>>> on testing branch[1]. So that I add my comment with my clean-up case.
>>>>> [1] https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing-passive-gov__;!!CTRNKA9wMg0ARbw!zIrzeDp9vPnm1_SDzVPuzqdHn3zWie9DnfBXaA-j9-CSrVc6aR9_rJQQiw81_CgAPh9XRRs$
>>>>>
>>>>> And 'Saravana Kannan <skannan@...eaurora.org>' is wrong email address.
>>>>> Please update the email or drop this email.
>>>>
>>>> Hi Chanwoo,
>>>>
>>>> Thank you for the advices.
>>>> I will resend patch v9 (add to linux-pm ML), remove this patch, and note
>>>> that my patch set base on
>>>> https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing-passive-gov__;!!CTRNKA9wMg0ARbw!yUlsuxrL5PcbF7o6A9DlCfvoA6w8V8VXKjYIybYyiJg3D0HM-lI2xRuxLUV6b3UJ8WFhg_g$
>>>
>>> I has not yet test this patch[1] on devfreq-testing-passive-gov branch.
>>> So that if possible, I'd like you to test your patches with this patch[1]
>>> and then if there is no problem, could you send the next patches with patch[1]?
>>>
>>> [1]https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-testing-passive-gov&id=39c80d11a8f42dd63ecea1e0df595a0ceb83b454__;!!CTRNKA9wMg0ARbw!yUlsuxrL5PcbF7o6A9DlCfvoA6w8V8VXKjYIybYyiJg3D0HM-lI2xRuxLUV6b3UJR2cQqZs$
>>
>>
>> Sorry for the confusion. I make the devfreq-testing-passive-gov[1]
>> branch based on latest devfreq-next branch.
>> [1] https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing-passive-gov__;!!CTRNKA9wMg0ARbw!yUlsuxrL5PcbF7o6A9DlCfvoA6w8V8VXKjYIybYyiJg3D0HM-lI2xRuxLUV6b3UJ8WFhg_g$
>>
>> First of all, if possible, I want to test them[1] with your patches in this series.
>> And then if there are no any problem, please let me know. After confirmed from you,
>> I'll send the patches of devfreq-testing-passive-gov[1] branch.
>> How about that?
>>
> Hi Chanwoo~
>
> We will use this on Google Chrome project.
> Google Hsin-Yi has test your patch + my patch set v8 [2~8]
>
> make sure cci devfreqs runs with cpufreq.
> suspend resume
> speedometer2 benchmark
> It is okay.
>
> Please send the patches of devfreq-testing-passive-gov[1] branch.
>
> I will send patch v9 base on yours latter.
Thanks for your test. I'll send the patches today.
>
>
>>
>>>
>>>>
>>>>
>>>>>
>>>>>
>>>>> On 3/23/21 8:33 PM, Andrew-sh.Cheng wrote:
>>>>>> From: Saravana Kannan <skannan@...eaurora.org>
>>>>>>
>>>>>> 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
>>>>>> after kernel-5.7
>>>>>> Don't return -EINVAL in devfreq_passive_event_handler()
>>>>>> since it doesn't handle DEVFREQ_GOV_SUSPEND DEVFREQ_GOV_RESUME cases.
>>>>>>
>>>>>> Signed-off-by: Saravana Kannan <skannan@...eaurora.org>
>>>>>> [Sibi: Integrated cpu-freqmap governor into passive_governor]
>>>>>> Signed-off-by: Sibi Sankar <sibis@...eaurora.org>
>>>>>> Signed-off-by: Andrew-sh.Cheng <andrew-sh.cheng@...iatek.com>
>>>>>> ---
>>>>>> drivers/devfreq/Kconfig | 2 +
>>>>>> drivers/devfreq/governor_passive.c | 329 +++++++++++++++++++++++++++++++++++--
>>>>>> include/linux/devfreq.h | 29 +++-
>>>>>> 3 files changed, 342 insertions(+), 18 deletions(-)
>>>>>>
>>>>>> diff --git a/drivers/devfreq/Kconfig b/drivers/devfreq/Kconfig
>>>>>> index 00704efe6398..f56132b0ae64 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 b094132bd20b..9cc57b083839 100644
>>>>>> --- a/drivers/devfreq/governor_passive.c
>>>>>> +++ b/drivers/devfreq/governor_passive.c
>>>>>> @@ -8,11 +8,103 @@
>>>>>> */
>>>>>>
>>>>>> #include <linux/module.h>
>>>>>> +#include <linux/cpu.h>
>>>>>> +#include <linux/cpufreq.h>
>>>>>> +#include <linux/cpumask.h>
>>>>>> #include <linux/device.h>
>>>>>> #include <linux/devfreq.h>
>>>>>> +#include <linux/slab.h>
>>>>>> #include "governor.h"
>>>>>>
>>>>>> -static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>> +struct devfreq_cpu_state {
>>>>>> + unsigned int curr_freq;
>>>>>> + unsigned int min_freq;
>>>>>> + unsigned int max_freq;
>>>>>> + unsigned int first_cpu;
>>>>>> + struct device *cpu_dev;
>>>>>> + struct opp_table *opp_table;
>>>>>> +};
>>>>>
>>>>> As I knew, the previous version has the description of structure
>>>>> as following: I wan to add the description like below.
>>>>>
>>>>> And if you have no any objection, I'd like you to order
>>>>> the variables as following and use 'dev' instead of 'cpu_dev'
>>>>> because this patch use the 'cpu_state->cpu_dev' at the multiple points.
>>>>> I think that 'cpu_state->dev' is better than 'cpu_state->cpu_dev'.
>>>>> Also, I prefer to use 'cur_freq' instead of 'curr_freq'
>>>>> because devfreq subsystem uses 'cur_freq' for expressing the 'current frequency'.
>>>>>
>>>>> /**
>>>>> * struct devfreq_cpu_state - Hold the per-cpu data
>>>>> * @dev: reference to cpu device.
>>>>> * @first_cpu: the cpumask of the first cpu of a policy.
>>>>> * @opp_table: reference to cpu opp table.
>>>>> * @cur_freq: the current frequency of the cpu.
>>>>> * @min_freq: the min frequency of the cpu.
>>>>> * @max_freq: the max frequency of the cpu.
>>>>> *
>>>>> * This structure stores the required cpu_data of a cpu.
>>>>> * This is auto-populated by the governor.
>>>>> */
>>>>> struct devfreq_cpu_state {
>>>>> struct device *dev;
>>>>> unsigned int first_cpu;
>>>>>
>>>>> struct opp_table *opp_table;
>>>>> unsigned int cur_freq;
>>>>> unsigned int min_freq;
>>>>> unsigned int max_freq;
>>>>> };
>>>>>
>>>>>
>>>>>> +
>>>>>> +static unsigned long xlate_cpufreq_to_devfreq(struct devfreq_passive_data *data,
>>>>>> + unsigned int cpu)
>>>>>> +{
>>>>>> + unsigned int cpu_min_freq, cpu_max_freq, cpu_curr_freq_khz, cpu_percent;
>>>>>> + unsigned long dev_min_freq, dev_max_freq, dev_max_state;
>>>>>> +
>>>>>> + struct devfreq_cpu_state *cpu_state = data->cpu_state[cpu];
>>>>>> + struct devfreq *devfreq = (struct devfreq *)data->this;
>>>>>> + unsigned long *dev_freq_table = devfreq->profile->freq_table;
>>>>>> + struct dev_pm_opp *opp = NULL, *p_opp = NULL;
>>>>>> + unsigned long cpu_curr_freq, freq;
>>>>>> +
>>>>>> + if (!cpu_state || cpu_state->first_cpu != cpu ||
>>>>>> + !cpu_state->opp_table || !devfreq->opp_table)
>>>>>> + return 0;
>>>>>> +
>>>>>> + cpu_curr_freq = cpu_state->curr_freq * 1000;
>>>>>> + p_opp = devfreq_recommended_opp(cpu_state->cpu_dev, &cpu_curr_freq, 0);
>>>>>> + if (IS_ERR(p_opp))
>>>>>> + return 0;
>>>>>> +
>>>>>> + opp = dev_pm_opp_xlate_required_opp(cpu_state->opp_table,
>>>>>> + devfreq->opp_table, p_opp);
>>>>>> + dev_pm_opp_put(p_opp);
>>>>>> +
>>>>>> + if (!IS_ERR(opp)) {
>>>>>> + freq = dev_pm_opp_get_freq(opp);
>>>>>> + dev_pm_opp_put(opp);
>>>>>> + goto out;
>>>>>> + }
>>>>>> +
>>>>>> + /* Use Interpolation if required opps is not available */
>>>>>> + cpu_min_freq = cpu_state->min_freq;
>>>>>> + cpu_max_freq = cpu_state->max_freq;
>>>>>> + cpu_curr_freq_khz = cpu_state->curr_freq;
>>>>>> +
>>>>>> + if (dev_freq_table) {
>>>>>> + /* Get minimum frequency according to sorting order */
>>>>>> + dev_max_state = dev_freq_table[devfreq->profile->max_state - 1];
>>>>>> + if (dev_freq_table[0] < dev_max_state) {
>>>>>> + dev_min_freq = dev_freq_table[0];
>>>>>> + dev_max_freq = dev_max_state;
>>>>>> + } else {
>>>>>> + dev_min_freq = dev_max_state;
>>>>>> + dev_max_freq = dev_freq_table[0];
>>>>>> + }
>>>>>> + } else {
>>>>>> + dev_min_freq = dev_pm_qos_read_value(devfreq->dev.parent,
>>>>>> + DEV_PM_QOS_MIN_FREQUENCY);
>>>>>> + dev_max_freq = dev_pm_qos_read_value(devfreq->dev.parent,
>>>>>> + DEV_PM_QOS_MAX_FREQUENCY);
>>>>>> +
>>>>>> + if (dev_max_freq <= dev_min_freq)
>>>>>> + return 0;
>>>>>> + }
>>>>>> + cpu_percent = ((cpu_curr_freq_khz - cpu_min_freq) * 100) / cpu_max_freq - cpu_min_freq;
>>>>>> + freq = dev_min_freq + mult_frac(dev_max_freq - dev_min_freq, cpu_percent, 100);
>>>>>> +
>>>>>> +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;
>>>>>> + unsigned long target_freq = 0;
>>>>>> +
>>>>>> + for_each_online_cpu(cpu)
>>>>>> + target_freq = max(target_freq,
>>>>>> + xlate_cpufreq_to_devfreq(p_data, cpu));
>>>>>> +
>>>>>> + *freq = target_freq;
>>>>>> +
>>>>>> + return 0;
>>>>>> +}
>>>>>
>>>>> As you knew, governor_passive.c was already used
>>>>> both 'dev_pm_opp_xlate_required_opp' and 'devfreq_recommended_opp'
>>>>> to get the target from OPP. So, I wan to make the common function
>>>>> like 'get_taget_freq_by_required_opp' as following:
>>>>> If define 'get_taget_freq_by_required_opp' as following,
>>>>> it will be used for get_target_freq_with_devfreq().
>>>>> After finisied the review of this patch, I'll send the patch[2].
>>>>> [2] https://urldefense.com/v3/__https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-testing-passive-gov&id=101c5a087586ab2b5cf3370166a7e39227ca83cf__;!!CTRNKA9wMg0ARbw!zIrzeDp9vPnm1_SDzVPuzqdHn3zWie9DnfBXaA-j9-CSrVc6aR9_rJQQiw81_CgA6mp3Yqo$
>>>>>
>>>>> For example but this code is not tested,
>>>>> static unsigned long get_taget_freq_by_required_opp(struct device *p_dev,
>>>>> struct opp_table *p_opp_table,
>>>>> struct opp_table *opp_table,
>>>>> unsigned long freq)
>>>>> {
>>>>> struct dev_pm_opp *opp = NULL, *p_opp = NULL;
>>>>>
>>>>> if (!p_dev || !p_opp_table || !opp_table || !freq)
>>>>> return 0;
>>>>>
>>>>> p_opp = devfreq_recommended_opp(p_dev, &freq, 0);
>>>>> if (IS_ERR(p_opp))
>>>>> return 0;
>>>>>
>>>>> opp = dev_pm_opp_xlate_required_opp(p_opp_table, opp_table, p_opp);
>>>>> dev_pm_opp_put(p_opp);
>>>>>
>>>>> if (IS_ERR(opp))
>>>>> return 0;
>>>>>
>>>>> freq = dev_pm_opp_get_freq(opp);
>>>>> dev_pm_opp_put(opp);
>>>>>
>>>>> return freq;
>>>>> }
>>>>>
>>>>> static int get_target_freq_with_cpufreq(struct devfreq *devfreq,
>>>>> unsigned long *target_freq)
>>>>> {
>>>>> struct devfreq_passive_data *p_data =
>>>>> (struct devfreq_passive_data *)devfreq->data;
>>>>> struct devfreq_cpu_data *cpu_data;
>>>>> unsigned long cpu, cpu_cur, cpu_min, cpu_max, cpu_percent;
>>>>> unsigned long dev_min, dev_max;
>>>>> unsigned long freq = 0;
>>>>>
>>>>> for_each_online_cpu(cpu) {
>>>>> cpu_data = p_data->cpu_data[cpu];
>>>>> if (!cpu_data || cpu_data->first_cpu != cpu)
>>>>> continue;
>>>>>
>>>>> /* Get target freq via required opps */
>>>>> cpu_cur = cpu_data->cur_freq * HZ_PER_KHZ;
>>>>> freq = get_taget_freq_by_required_opp(cpu_data->dev,
>>>>> cpu_data->opp_table,
>>>>> devfreq->opp_table, cpu_cur);
>>>>> if (freq) {
>>>>> *target_freq = max(freq, *target_freq);
>>>>> continue;
>>>>> }
>>>>>
>>>>> /* Use Interpolation if required opps is not available */
>>>>> devfreq_get_freq_range(devfreq, &dev_min, &dev_max);
>>>>>
>>>>> cpu_min = cpu_data->min_freq;
>>>>> cpu_max = cpu_data->max_freq;
>>>>> cpu_cur = cpu_data->cur_freq;
>>>>>
>>>>> cpu_percent = ((cpu_cur - cpu_min) * 100) / cpu_max - cpu_min;
>>>>> freq = dev_min + mult_frac(dev_max - dev_min, cpu_percent, 100);
>>>>>
>>>>> *target_freq = max(freq, *target_freq);
>>>>> }
>>>>>
>>>>> return 0;
>>>>> }
>>>>>
>>>>>> +
>>>>>> +static int get_target_freq_with_devfreq(struct devfreq *devfreq,
>>>>>> unsigned long *freq)
>>>>>> {
>>>>>> struct devfreq_passive_data *p_data
>>>>>> @@ -23,14 +115,6 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>> int i, count;
>>>>>>
>>>>>> /*
>>>>>> - * 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);
>>>>>> -
>>>>>> - /*
>>>>>> * If the parent and passive devfreq device uses the OPP table,
>>>>>> * get the next frequency by using the OPP table.
>>>>>> */
>>>>>> @@ -98,6 +182,37 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>>>>>> return 0;
>>>>>> }
>>>>>>
>>>>>> +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 devfreq_passive_notifier_call(struct notifier_block *nb,
>>>>>> unsigned long event, void *ptr)
>>>>>> {
>>>>>> @@ -130,16 +245,200 @@ 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 *cpu_freq = ptr;
>>>>>
>>>>> Use 'freqs' variable name. I prefer to use the same variable name
>>>>> for both devfreq_freqs and cpufreq_freqs instance.
>>>>>
>>>>>> + unsigned int curr_freq;
>>>>>
>>>>> As I commented above, better to use 'cur_frq' instead of 'curr_freq'
>>>>> if there is no any special reason.
>>>>>
>>>>>> + int ret;
>>>>>> +
>>>>>> + if (event != CPUFREQ_POSTCHANGE || !cpu_freq ||
>>>>>> + !data->cpu_state[cpu_freq->policy->cpu])
>>>>>> + return 0;
>>>>>> +
>>>>>> + cpu_state = data->cpu_state[cpu_freq->policy->cpu];
>>>>>> + if (cpu_state->curr_freq == cpu_freq->new)
>>>>>> + return 0;
>>>>>> +
>>>>>> + /* Backup current freq and pre-update cpu state freq*/
>>>>>
>>>>> I think that this commnet is not critial. So, please drop this comment.
>>>>>
>>>>>> + curr_freq = cpu_state->curr_freq;
>>>>>> + cpu_state->curr_freq = cpu_freq->new;
>>>>>> +
>>>>>> + mutex_lock(&devfreq->lock);
>>>>>> + ret = update_devfreq(devfreq);
>>>>>
>>>>> I recommend to use 'devfreq_update_target' instead of 'update_devfreq'
>>>>> as following:
>>>>> devfreq_update_target(devfreq, freqs->new);
>>>>>
>>>>>> + mutex_unlock(&devfreq->lock);
>>>>>> + if (ret) {
>>>>>> + cpu_state->curr_freq = curr_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)
>>>>>
>>>>> In order to keep the consistent style of function name,
>>>>> please change the name as following because devfreq defines
>>>>> the function name as 'devfreq_regiter_notifier'
>>>>> - cpufreq_passive_register -> cpufreq_passive_register_notifier
>>>>>
>>>>>> +{
>>>>>> + 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 *cpu_state;
>>>>>> + struct cpufreq_policy *policy;
>>>>>> + struct device *cpu_dev;
>>>>>> + unsigned int cpu;
>>>>>> + int ret;
>>>>>> +
>>>>>> + get_online_cpus();
>>>>>> +
>>>>>> + 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 */
>>>>>
>>>>> Don't need this comment. Please drop it.
>>>>>
>>>>>> + for_each_online_cpu(cpu) {
>>>>>> + if (data->cpu_state[cpu])
>>>>>> + continue;
>>>>>> +
>>>>>> + policy = cpufreq_cpu_get(cpu);
>>>>>> + if (!policy) {
>>>>>> + ret = -EINVAL;
>>>>>> + goto out;
>>>>>> + } else if (PTR_ERR(policy) == -EPROBE_DEFER) {
>>>>>> + ret = -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;
>>>>>> + }
>>>>>
>>>>> Use dev_err_probe() funciotn to handle hte EPROBE_DEFER.
>>>>> It make code more simple.
>>>>>
>>>>>> +
>>>>>> + cpu_state = kzalloc(sizeof(*cpu_state), GFP_KERNEL);
>>>>>> + if (!cpu_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;
>>>>>> + }
>>>>>> +
>>>>>> + cpu_state->cpu_dev = cpu_dev;
>>>>>> + cpu_state->opp_table = opp_table;
>>>>>> + cpu_state->first_cpu = cpumask_first(policy->related_cpus);
>>>>>> + cpu_state->curr_freq = policy->cur;
>>>>>> + cpu_state->min_freq = policy->cpuinfo.min_freq;
>>>>>> + cpu_state->max_freq = policy->cpuinfo.max_freq;
>>>>>> + data->cpu_state[cpu] = cpu_state;
>>>>>> +
>>>>>> + cpufreq_cpu_put(policy);
>>>>>> + }
>>>>>> +
>>>>>> +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)
>>>>>
>>>>> As I commented above, please change the name as following:
>>>>> - cpufreq_passive_unregister -> cpufreq_passive_unregister_notifier
>>>>>
>>>>>> +{
>>>>>> + 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;
>>>>>> +}
>>>>>> +
>>>>>> +int register_parent_dev_notifier(struct devfreq_passive_data **p_data)
>>>>>> +{
>>>>>> + struct notifier_block *nb = &(*p_data)->nb;
>>>>>> + int ret = 0;
>>>>>> +
>>>>>> + switch ((*p_data)->parent_type) {
>>>>>> + case DEVFREQ_PARENT_DEV:
>>>>>> + nb->notifier_call = devfreq_passive_notifier_call;
>>>>>> + ret = devfreq_register_notifier((struct devfreq *)(*p_data)->parent, nb,
>>>>>> + DEVFREQ_TRANSITION_NOTIFIER);
>>>>>> + break;
>>>>>> + case CPUFREQ_PARENT_DEV:
>>>>>> + ret = cpufreq_passive_register(p_data);
>>>>>> + break;
>>>>>> + default:
>>>>>> + ret = -EINVAL;
>>>>>> + break;
>>>>>> + }
>>>>>> + return ret;
>>>>>> +}
>>>>>> +
>>>>>> +int unregister_parent_dev_notifier(struct devfreq_passive_data **p_data)
>>>>>> +{
>>>>>> + int ret = 0;
>>>>>> +
>>>>>> + switch ((*p_data)->parent_type) {
>>>>>> + case DEVFREQ_PARENT_DEV:
>>>>>> + WARN_ON(devfreq_unregister_notifier((struct devfreq *)(*p_data)->parent,
>>>>>> + &(*p_data)->nb,
>>>>>> + DEVFREQ_TRANSITION_NOTIFIER));
>>>>>> + break;
>>>>>> + case CPUFREQ_PARENT_DEV:
>>>>>> + cpufreq_passive_unregister(p_data);
>>>>>> + break;
>>>>>> + default:
>>>>>> + ret = -EINVAL;
>>>>>> + break;
>>>>>> + }
>>>>>> + return ret;
>>>>>> +}
>>>>>
>>>>> I think that you don't need to define register_parent_dev_notifier
>>>>> and unregister_parent_dev_notifier as the separate functions.
>>>>>
>>>>> Instead of the separate functions, just add the code
>>>>> into devfreq_passive_event_handler.
>>>>>
>>>>>
>>>>>> +
>>>>>> static int devfreq_passive_event_handler(struct devfreq *devfreq,
>>>>>> unsigned int event, void *data)
>>>>>> {
>>>>>> struct devfreq_passive_data *p_data
>>>>>> = (struct devfreq_passive_data *)devfreq->data;
>>>>>> struct devfreq *parent = (struct devfreq *)p_data->parent;
>>>>>> - struct notifier_block *nb = &p_data->nb;
>>>>>> int ret = 0;
>>>>>>
>>>>>> - if (!parent)
>>>>>> + if (p_data->parent_type == DEVFREQ_PARENT_DEV && !parent)
>>>>>> return -EPROBE_DEFER;
>>>>>>
>>>>>> switch (event) {
>>>>>> @@ -147,13 +446,11 @@ 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);
>>>>>> + ret = register_parent_dev_notifier(&p_data);
>>>>>> break;
>>>>>> +
>>>>>> case DEVFREQ_GOV_STOP:
>>>>>> - WARN_ON(devfreq_unregister_notifier(parent, nb,
>>>>>> - DEVFREQ_TRANSITION_NOTIFIER));
>>>>>> + ret = unregister_parent_dev_notifier(&p_data);
>>>>>> break;
>>>>>> default:
>>>>>> break;
>>>>>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>>>>>> index 26ea0850be9b..e0093b7c805c 100644
>>>>>> --- a/include/linux/devfreq.h
>>>>>> +++ b/include/linux/devfreq.h
>>>>>> @@ -280,6 +280,25 @@ 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;
>>>>>> +
>>>>>> +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.
>>>>>> @@ -290,13 +309,15 @@ 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.
>>>>>> + * @parent_type: parent type of the device
>>>>>> * @this: the devfreq instance of own device.
>>>>>> * @nb: the notifier block for DEVFREQ_TRANSITION_NOTIFIER list
>>>>>> + * @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 */
>>>>>> @@ -305,9 +326,13 @@ 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
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