Hello,

On Fri, Aug 17, 2012 at 10:58 AM, Amit Kachhap <amit.kach...@linaro.org> wrote:
> On 17 August 2012 12:54, Zhang Rui <rui.zh...@intel.com> wrote:
>> On 四, 2012-08-16 at 17:11 +0530, Amit Daniel Kachhap wrote:
>>> This patchset introduces a new generic cooling device based on cpufreq
>>> that can be used on non-ACPI platforms.  As a proof of concept, we have
>>> drivers for the following platforms using this mechanism now:
>>>
>>>  * Samsung Exynos (Exynos4 and Exynos5) in the current patchset.
>>>  * Freescale i.MX (git://git.linaro.org/people/amitdanielk/linux.git 
>>> imx6q_thermal)
>>>
>>> There is a small change in cpufreq cooling registration APIs, so a minor
>>> change is needed for Freescale platforms.
>>>
>>> Brief Description:
>>>
>>> 1) The generic cooling devices code is placed inside driver/thermal/*
>>>    as placing inside acpi folder will need un-necessary enabling of acpi
>>>    code.  This code is architecture independent.
>>>
>>> 2) This patchset adds generic cpu cooling low level implementation
>>>    through frequency clipping.  In future, other cpu related cooling
>>>    devices may be added here.  An ACPI version of this already exists
>>>    (drivers/acpi/processor_thermal.c) .But this will be useful for
>>>    platforms like ARM using the generic thermal interface along with the
>>>    generic cpu cooling devices.  The cooling device registration API's
>>>    return cooling device pointers which can be easily binded with the
>>>    thermal zone trip points.  The important APIs exposed are,
>>>
>>>    a) struct thermal_cooling_device *cpufreq_cooling_register(
>>>         struct cpumask *clip_cpus)
>>>    b) void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
>>>
>>> 3) Samsung exynos platform thermal implementation is done using the
>>>    generic cpu cooling APIs and the new trip type.  The temperature sensor
>>>    driver present in the hwmon folder(registered as hwmon driver) is moved
>>>    to thermal folder and registered as a thermal driver.
>>>
>>> A simple data/control flow diagrams is shown below,
>>>
>>> Core Linux thermal <----->  Exynos thermal interface <----- Temperature 
>>> Sensor
>>>           |                             |
>>>          \|/                            |
>>>   Cpufreq cooling device <---------------
>>>
>>> TODO:
>>> *Will send the DT enablement patches later after the driver is merged.
>>>
>>> This patch:
>>>
>>> Add support for generic cpu thermal cooling low level implementations
>>> using frequency scaling up/down based on the registration parameters.
>>> Different cpu related cooling devices can be registered by the user and
>>> the binding of these cooling devices to the corresponding trip points can
>>> be easily done as the registration APIs return the cooling device pointer.
>>> The user of these APIs are responsible for passing clipping frequency .
>>> The drivers can also register to recieve notification about any cooling
>>> action called.
>>>
>>> [a...@linux-foundation.org: fix comment layout]
>>> Signed-off-by: Amit Daniel Kachhap <amit.kach...@linaro.org>
>>> Cc: Guenter Roeck <guenter.ro...@ericsson.com>
>>> Cc: SangWook Ju <sw...@samsung.com>
>>> Cc: Durgadoss <durgados...@intel.com>
>>> Cc: Len Brown <l...@kernel.org>
>>> Cc: Jean Delvare <kh...@linux-fr.org>
>>> Cc: Kyungmin Park <kmp...@infradead.org>
>>> Cc: Kukjin Kim <kgene....@samsung.com>
>>> Signed-off-by: Andrew Morton <a...@linux-foundation.org>
>>> Signed-off-by: Amit Daniel Kachhap <amit.dan...@samsung.com>
>>> ---
>>>  Documentation/thermal/cpu-cooling-api.txt |   52 +++
>>>  drivers/thermal/Kconfig                   |   11 +
>>>  drivers/thermal/Makefile                  |    1 +
>>>  drivers/thermal/cpu_cooling.c             |  512 
>>> +++++++++++++++++++++++++++++
>>>  include/linux/cpu_cooling.h               |   79 +++++
>>>  5 files changed, 655 insertions(+), 0 deletions(-)
>>>  create mode 100644 Documentation/thermal/cpu-cooling-api.txt
>>>  create mode 100644 drivers/thermal/cpu_cooling.c
>>>  create mode 100644 include/linux/cpu_cooling.h
>>>
>>> diff --git a/Documentation/thermal/cpu-cooling-api.txt 
>>> b/Documentation/thermal/cpu-cooling-api.txt
>>> new file mode 100644
>>> index 0000000..a1f2a6b
>>> --- /dev/null
>>> +++ b/Documentation/thermal/cpu-cooling-api.txt
>>> @@ -0,0 +1,52 @@
>>> +CPU cooling APIs How To
>>> +===================================
>>> +
>>> +Written by Amit Daniel Kachhap <amit.kach...@linaro.org>
>>> +
>>> +Updated: 12 May 2012
>>> +
>>> +Copyright (c)  2012 Samsung Electronics Co., Ltd(http://www.samsung.com)
>>> +
>>> +0. Introduction
>>> +
>>> +The generic cpu cooling(freq clipping) provides 
>>> registration/unregistration APIs
>>> +to the caller. The binding of the cooling devices to the trip point is 
>>> left for
>>> +the user. The registration APIs returns the cooling device pointer.
>>> +
>>> +1. cpu cooling APIs
>>> +
>>> +1.1 cpufreq registration/unregistration APIs
>>> +1.1.1 struct thermal_cooling_device *cpufreq_cooling_register(
>>> +     struct cpumask *clip_cpus)
>>> +
>>> +    This interface function registers the cpufreq cooling device with the 
>>> name
>>> +    "thermal-cpufreq-%x". This api can support multiple instances of 
>>> cpufreq
>>> +    cooling devices.
>>> +
>>> +   clip_cpus: cpumask of cpus where the frequency constraints will happen.
>>> +
>>> +1.1.2 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
>>> +
>>> +    This interface function unregisters the "thermal-cpufreq-%x" cooling 
>>> device.
>>> +
>>> +    cdev: Cooling device pointer which has to be unregistered.
>>> +
>>> +
>>> +1.2 CPU cooling action notifier register/unregister interface
>>> +1.2.1 int cputherm_register_notifier(struct notifier_block *nb,
>>> +     unsigned int list)
>>> +
>>> +    This interface registers a driver with cpu cooling layer. The driver 
>>> will
>>> +    be notified when any cpu cooling action is called.
>>> +
>>> +    nb: notifier function to register
>>> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
>>> +
>>> +1.2.2 int cputherm_unregister_notifier(struct notifier_block *nb,
>>> +     unsigned int list)
>>> +
>>> +    This interface registers a driver with cpu cooling layer. The driver 
>>> will
>>> +    be notified when any cpu cooling action is called.
>>> +
>>> +    nb: notifier function to register
>>> +    list: CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP
>>
>> what are these two APIs used for?
>> I did not see they are used in your patch set, do I miss something?
> No currently they are not used by my patches. I added them on request
> from Eduardo and others

Yeah, this was a suggestion as we didn't really know how the FW part
would evolve by that time.

The reasoning is to allow any interested user (in kernel) to be
notified when max frequency changes. Actually, the use case behind
this is to allow such users to perform some handshaking or stop their
activities or even change some paramenters, in case the max frequency
would change. Ideally it would be possible to nack the cooling
transition. But that is yet a wider discussion. So far we don't have
users for this.

>>
>>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>>> index 7dd8c34..996003b 100644
>>> --- a/drivers/thermal/Kconfig
>>> +++ b/drivers/thermal/Kconfig
>>> @@ -19,6 +19,17 @@ config THERMAL_HWMON
>>>       depends on HWMON=y || HWMON=THERMAL
>>>       default y
>>>
>>> +config CPU_THERMAL
>>> +     bool "generic cpu cooling support"
>>> +     depends on THERMAL && CPU_FREQ
>>> +     help
>>> +       This implements the generic cpu cooling mechanism through frequency
>>> +       reduction, cpu hotplug and any other ways of reducing temperature. 
>>> An
>>> +       ACPI version of this already 
>>> exists(drivers/acpi/processor_thermal.c).
>>> +       This will be useful for platforms using the generic thermal 
>>> interface
>>> +       and not the ACPI interface.
>>> +       If you want this support, you should say Y here.
>>> +
>>>  config SPEAR_THERMAL
>>>       bool "SPEAr thermal sensor driver"
>>>       depends on THERMAL
>>> diff --git a/drivers/thermal/Makefile b/drivers/thermal/Makefile
>>> index fd9369a..aae59ad 100644
>>> --- a/drivers/thermal/Makefile
>>> +++ b/drivers/thermal/Makefile
>>> @@ -3,5 +3,6 @@
>>>  #
>>>
>>>  obj-$(CONFIG_THERMAL)                += thermal_sys.o
>>> +obj-$(CONFIG_CPU_THERMAL)            += cpu_cooling.o
>>>  obj-$(CONFIG_SPEAR_THERMAL)          += spear_thermal.o
>>>  obj-$(CONFIG_RCAR_THERMAL)   += rcar_thermal.o
>>> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
>>> new file mode 100644
>>> index 0000000..c42e557
>>> --- /dev/null
>>> +++ b/drivers/thermal/cpu_cooling.c
>>> @@ -0,0 +1,512 @@
>>> +/*
>>> + *  linux/drivers/thermal/cpu_cooling.c
>>> + *
>>> + *  Copyright (C) 2012       Samsung Electronics Co., 
>>> Ltd(http://www.samsung.com)
>>> + *  Copyright (C) 2012  Amit Daniel <amit.kach...@linaro.org>
>>> + *
>>> + * 
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> + *  This program is free software; you can redistribute it and/or modify
>>> + *  it under the terms of the GNU General Public License as published by
>>> + *  the Free Software Foundation; version 2 of the License.
>>> + *
>>> + *  This program is distributed in the hope that it will be useful, but
>>> + *  WITHOUT ANY WARRANTY; without even the implied warranty of
>>> + *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
>>> + *  General Public License for more details.
>>> + *
>>> + *  You should have received a copy of the GNU General Public License along
>>> + *  with this program; if not, write to the Free Software Foundation, Inc.,
>>> + *  59 Temple Place, Suite 330, Boston, MA 02111-1307 USA.
>>> + *
>>> + * 
>>> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>> + */
>>> +#include <linux/kernel.h>
>>> +#include <linux/module.h>
>>> +#include <linux/thermal.h>
>>> +#include <linux/platform_device.h>
>>> +#include <linux/cpufreq.h>
>>> +#include <linux/err.h>
>>> +#include <linux/slab.h>
>>> +#include <linux/cpu.h>
>>> +#include <linux/cpu_cooling.h>
>>> +
>>> +/**
>>> + * struct cpufreq_cooling_device
>>> + * @id: unique integer value corresponding to each cpufreq_cooling_device
>>> + *   registered.
>>> + * @cool_dev: thermal_cooling_device pointer to keep track of the the
>>> + *   egistered cooling device.
>>> + * @cpufreq_state: integer value representing the current state of cpufreq
>>> + *   cooling devices.
>>> + * @cpufreq_val: integer value representing the absolute value of the 
>>> clipped
>>> + *   frequency.
>>> + * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
>>> + * @node: list_head to link all cpufreq_cooling_device together.
>>> + *
>>> + * This structure is required for keeping information of each
>>> + * cpufreq_cooling_device registered as a list whose head is represented by
>>> + * cooling_cpufreq_list. In order to prevent corruption of this list a
>>> + * mutex lock cooling_cpufreq_lock is used.
>>> + */
>>> +struct cpufreq_cooling_device {
>>> +     int id;
>>> +     struct thermal_cooling_device *cool_dev;
>>> +     unsigned int cpufreq_state;
>>> +     unsigned int cpufreq_val;
>>> +     struct cpumask allowed_cpus;
>>> +     struct list_head node;
>>> +};
>>> +static LIST_HEAD(cooling_cpufreq_list);
>>> +static DEFINE_IDR(cpufreq_idr);
>>> +
>>> +static struct mutex cooling_cpufreq_lock;
>>> +
>>> +/* notify_table passes value to the CPUFREQ_ADJUST callback function. */
>>> +#define NOTIFY_INVALID NULL
>>> +struct cpufreq_cooling_device *notify_device;
>>> +
>>> +/* Head of the blocking notifier chain to inform about frequency clamping 
>>> */
>>> +static BLOCKING_NOTIFIER_HEAD(cputherm_state_notifier_list);
>>> +
>>> +/**
>>> + * get_idr - function to get a unique id.
>>> + * @idr: struct idr * handle used to create a id.
>>> + * @id: int * value generated by this function.
>>> + */
>>> +static int get_idr(struct idr *idr, int *id)
>>> +{
>>> +     int err;
>>> +again:
>>> +     if (unlikely(idr_pre_get(idr, GFP_KERNEL) == 0))
>>> +             return -ENOMEM;
>>> +
>>> +     mutex_lock(&cooling_cpufreq_lock);
>>> +     err = idr_get_new(idr, NULL, id);
>>> +     mutex_unlock(&cooling_cpufreq_lock);
>>> +
>>> +     if (unlikely(err == -EAGAIN))
>>> +             goto again;
>>> +     else if (unlikely(err))
>>> +             return err;
>>> +
>>> +     *id = *id & MAX_ID_MASK;
>>> +     return 0;
>>> +}
>>> +
>>> +/**
>>> + * release_idr - function to free the unique id.
>>> + * @idr: struct idr * handle used for creating the id.
>>> + * @id: int value representing the unique id.
>>> + */
>>> +static void release_idr(struct idr *idr, int id)
>>> +{
>>> +     mutex_lock(&cooling_cpufreq_lock);
>>> +     idr_remove(idr, id);
>>> +     mutex_unlock(&cooling_cpufreq_lock);
>>> +}
>>> +
>>> +/**
>>> + * cputherm_register_notifier - Register a notifier with cpu cooling 
>>> interface.
>>> + * @nb:      struct notifier_block * with callback info.
>>> + * @list: integer value for which notification is needed. possible values 
>>> are
>>> + *   CPUFREQ_COOLING_START and CPUFREQ_COOLING_STOP.
>>> + *
>>> + * This exported function registers a driver with cpu cooling layer. The 
>>> driver
>>> + * will be notified when any cpu cooling action is called.
>>> + */
>>> +int cputherm_register_notifier(struct notifier_block *nb, unsigned int 
>>> list)
>>> +{
>>> +     int ret = 0;
>>> +
>>> +     switch (list) {
>>> +     case CPUFREQ_COOLING_START:
>>> +     case CPUFREQ_COOLING_STOP:
>>> +             ret = blocking_notifier_chain_register(
>>> +                             &cputherm_state_notifier_list, nb);
>>> +             break;
>>> +     default:
>>> +             ret = -EINVAL;
>>> +     }
>>> +     return ret;
>>> +}
>>> +EXPORT_SYMBOL(cputherm_register_notifier);
>>> +
>>> +/**
>>> + * cputherm_unregister_notifier - Un-register a notifier.
>>> + * @nb:      struct notifier_block * with callback info.
>>> + * @list: integer value for which notification is needed. values possible 
>>> are
>>> + *   CPUFREQ_COOLING_START or CPUFREQ_COOLING_STOP.
>>> + *
>>> + * This exported function un-registers a driver with cpu cooling layer.
>>> + */
>>> +int cputherm_unregister_notifier(struct notifier_block *nb, unsigned int 
>>> list)
>>> +{
>>> +     int ret = 0;
>>> +
>>> +     switch (list) {
>>> +     case CPUFREQ_COOLING_START:
>>> +     case CPUFREQ_COOLING_STOP:
>>> +             ret = blocking_notifier_chain_unregister(
>>> +                             &cputherm_state_notifier_list, nb);
>>> +             break;
>>> +     default:
>>> +             ret = -EINVAL;
>>> +     }
>>> +     return ret;
>>> +}
>>> +EXPORT_SYMBOL(cputherm_unregister_notifier);
>>> +
>>> +/* Below code defines functions to be used for cpufreq as cooling device */
>>> +
>>> +/**
>>> + * is_cpufreq_valid - function to check if a cpu has frequency transition 
>>> policy.
>>> + * @cpu: cpu for which check is needed.
>>> + */
>>> +static int is_cpufreq_valid(int cpu)
>>> +{
>>> +     struct cpufreq_policy policy;
>>> +     return !cpufreq_get_policy(&policy, cpu);
>>> +}
>>> +
>>> +/**
>>> + * get_cpu_frequency - get the absolute value of frequency from level.
>>> + * @cpu: cpu for which frequency is fetched.
>>> + * @level: level of frequency of the CPU
>>> + *   e.g level=1 --> 1st MAX FREQ, LEVEL=2 ---> 2nd MAX FREQ, .... etc
>>> + */
>>> +static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long 
>>> level)
>>> +{
>>> +     int ret = 0, i = 0;
>>> +     unsigned long level_index;
>>> +     bool descend = false;
>>> +     struct cpufreq_frequency_table *table =
>>> +                                     cpufreq_frequency_get_table(cpu);
>>> +     if (!table)
>>> +             return ret;
>>> +
>>> +     while (table[i].frequency != CPUFREQ_TABLE_END) {
>>> +             if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
>>> +                     continue;
>>> +
>>> +             /*check if table in ascending or descending order*/
>>> +             if ((table[i + 1].frequency != CPUFREQ_TABLE_END) &&
>>> +                     (table[i + 1].frequency < table[i].frequency)
>>> +                     && !descend) {
>>> +                     descend = true;
>>> +             }
>>> +
>>> +             /*return if level matched and table in descending order*/
>>> +             if (descend && i == level)
>>> +                     return table[i].frequency;
>>> +             i++;
>>> +     }
>>> +     i--;
>>> +
>>> +     if (level > i || descend)
>>> +             return ret;
>>> +     level_index = i - level;
>>> +
>>> +     /*Scan the table in reverse order and match the level*/
>>> +     while (i >= 0) {
>>> +             if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
>>> +                     continue;
>>> +             /*return if level matched*/
>>> +             if (i == level_index)
>>> +                     return table[i].frequency;
>>> +             i--;
>>> +     }
>>> +     return ret;
>>> +}
>>> +
>>> +/**
>>> + * cpufreq_apply_cooling - function to apply frequency clipping.
>>> + * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
>>> + *   clipping data.
>>> + * @cooling_state: value of the cooling state.
>>> + */
>>> +static int cpufreq_apply_cooling(struct cpufreq_cooling_device 
>>> *cpufreq_device,
>>> +                             unsigned long cooling_state)
>>> +{
>>> +     unsigned int event, cpuid, clip_freq;
>>> +     struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
>>> +     unsigned int cpu = cpumask_any(maskPtr);
>>> +
>>> +
>>> +     /* Check if the old cooling action is same as new cooling action */
>>> +     if (cpufreq_device->cpufreq_state == cooling_state)
>>> +             return 0;
>>> +
>>> +     clip_freq = get_cpu_frequency(cpu, cooling_state);
>>> +     if (!clip_freq)
>>> +             return -EINVAL;
>>> +
>>> +     cpufreq_device->cpufreq_state = cooling_state;
>>> +     cpufreq_device->cpufreq_val = clip_freq;
>>> +     notify_device = cpufreq_device;
>>> +
>>> +     if (cooling_state != 0)
>>> +             event = CPUFREQ_COOLING_START;
>>> +     else
>>> +             event = CPUFREQ_COOLING_STOP;
>>> +
>>> +     blocking_notifier_call_chain(&cputherm_state_notifier_list,
>>> +                                             event, &clip_freq);
>>> +
>>> +     for_each_cpu(cpuid, maskPtr) {
>>> +             if (is_cpufreq_valid(cpuid))
>>> +                     cpufreq_update_policy(cpuid);
>>> +     }
>>> +
>>> +     notify_device = NOTIFY_INVALID;
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +/**
>>> + * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
>>> + * @nb:      struct notifier_block * with callback info.
>>> + * @event: value showing cpufreq event for which this function invoked.
>>> + * @data: callback-specific data
>>> + */
>>> +static int cpufreq_thermal_notifier(struct notifier_block *nb,
>>> +                                     unsigned long event, void *data)
>>> +{
>>> +     struct cpufreq_policy *policy = data;
>>> +     unsigned long max_freq = 0;
>>> +
>>> +     if (event != CPUFREQ_ADJUST || notify_device == NOTIFY_INVALID)
>>> +             return 0;
>>> +
>>> +     if (cpumask_test_cpu(policy->cpu, &notify_device->allowed_cpus))
>>> +             max_freq = notify_device->cpufreq_val;
>>> +
>>> +     /* Never exceed user_policy.max*/
>>> +     if (max_freq > policy->user_policy.max)
>>> +             max_freq = policy->user_policy.max;
>>> +
>>> +     if (policy->max != max_freq)
>>> +             cpufreq_verify_within_limits(policy, 0, max_freq);
>>> +
>>> +     return 0;
>>> +}
>>> +
>>> +/*
>>> + * cpufreq cooling device callback functions are defined below
>>> + */
>>> +
>>> +/**
>>> + * cpufreq_get_max_state - callback function to get the max cooling state.
>>> + * @cdev: thermal cooling device pointer.
>>> + * @state: fill this variable with the max cooling state.
>>> + */
>>> +static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
>>> +                              unsigned long *state)
>>> +{
>>> +     int ret = -EINVAL, i = 0;
>>> +     struct cpufreq_cooling_device *cpufreq_device;
>>> +     struct cpumask *maskPtr;
>>> +     unsigned int cpu;
>>> +     struct cpufreq_frequency_table *table;
>>> +
>>> +     mutex_lock(&cooling_cpufreq_lock);
>>> +     list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>>> +             if (cpufreq_device && cpufreq_device->cool_dev == cdev)
>>> +                     break;
>>> +     }
>>> +     if (cpufreq_device == NULL)
>>> +             goto return_get_max_state;
>>> +
>>> +     maskPtr = &cpufreq_device->allowed_cpus;
>>> +     cpu = cpumask_any(maskPtr);
>>> +     table = cpufreq_frequency_get_table(cpu);
>>> +     if (!table) {
>>> +             *state = 0;
>>> +             ret = 0;
>>> +             goto return_get_max_state;
>>> +     }
>>> +
>>> +     while (table[i].frequency != CPUFREQ_TABLE_END) {
>>> +             if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
>>> +                     continue;
>>> +             i++;
>>> +     }
>>> +     if (i > 0) {
>>> +             *state = --i;
>>> +             ret = 0;
>>> +     }
>>> +
>>> +return_get_max_state:
>>> +     mutex_unlock(&cooling_cpufreq_lock);
>>> +     return ret;
>>> +}
>>> +
>>> +/**
>>> + * cpufreq_get_cur_state - callback function to get the current cooling 
>>> state.
>>> + * @cdev: thermal cooling device pointer.
>>> + * @state: fill this variable with the current cooling state.
>>> + */
>>> +static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
>>> +                              unsigned long *state)
>>> +{
>>> +     int ret = -EINVAL;
>>> +     struct cpufreq_cooling_device *cpufreq_device;
>>> +
>>> +     mutex_lock(&cooling_cpufreq_lock);
>>> +     list_for_each_entry(cpufreq_device, &cooling_cpufreq_list, node) {
>>> +             if (cpufreq_device && cpufreq_device->cool_dev == cdev) {
>>> +                     *state = cpufreq_device->cpufreq_state;
>>> +                     ret = 0;
>>> +                     break;
>>> +             }
>>> +     }
>>> +     mutex_unlock(&cooling_cpufreq_lock);
>>> +
>>
>> as cpufreq may be changed in other places, e.g. via sysfs I/F, we should
>> use the current cpu frequency to get the REAL cooling state, rather than
>> using a cached value.
>
> Yes agreed , I will repost with your suggestion.
>
> Thanks,
> Amit
>>
>> thanks,
>> rui
>>
>>
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-- 

Eduardo Valentin
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