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Message-ID: <7043f157-85a1-29d4-ac51-a0ed71322374@samsung.com>
Date: Thu, 25 Mar 2021 16:42:45 +0900
From: Chanwoo Choi <cw00.choi@...sung.com>
To: "Andrew-sh.Cheng" <andrew-sh.cheng@...iatek.com>,
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>
Cc: 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,
Saravana Kannan <skannan@...eaurora.org>,
Sibi Sankar <sibis@...eaurora.org>
Subject: Re: [PATCH V8 1/8] PM / devfreq: Add cpu based scaling support to
passive_governor
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://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/log/?h=devfreq-testing-passive-gov
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://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/commit/?h=devfreq-testing-passive-gov&id=101c5a087586ab2b5cf3370166a7e39227ca83cf
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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