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SubjectRe: [PATCH v3 2/5] devfreq: add support for suspend/resume of a devfreq device
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Hi Chanwoo,

On 12/6/18 2:17 AM, Chanwoo Choi wrote:
> Hi Lukasz,
>
> On 2018년 12월 05일 20:05, Lukasz Luba wrote:
>> The patch prepares devfreq device for handling suspend/resume
>> functionality. The new fields will store needed information during this
>> process. Devfreq framework handles opp-suspend DT entry and there is no
>> need of modyfications in the drivers code. It uses atomic variables to
>> make sure no race condition affects the process.
>>
>> Suggested-by: Tobias Jakobi <tjakobi@math.uni-bielefeld.de>
>> Suggested-by: Chanwoo Choi <cw00.choi@samsung.com>
>> Signed-off-by: Lukasz Luba <l.luba@partner.samsung.com>
>> ---
>> drivers/devfreq/devfreq.c | 47 +++++++++++++++++++++++++++++++++++++++++------
>> include/linux/devfreq.h | 7 +++++++
>> 2 files changed, 48 insertions(+), 6 deletions(-)
>
> Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Thank you for the review and comments for the whole patch series.

Regards,
Lukasz

>
>>
>> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
>> index a9fd61b..46517b6 100644
>> --- a/drivers/devfreq/devfreq.c
>> +++ b/drivers/devfreq/devfreq.c
>> @@ -316,6 +316,10 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
>> "Couldn't update frequency transition information.\n");
>>
>> devfreq->previous_freq = new_freq;
>> +
>> + if (devfreq->suspend_freq)
>> + devfreq->resume_freq = cur_freq;
>> +
>> return err;
>> }
>>
>> @@ -667,6 +671,9 @@ struct devfreq *devfreq_add_device(struct device *dev,
>> }
>> devfreq->max_freq = devfreq->scaling_max_freq;
>>
>> + devfreq->suspend_freq = dev_pm_opp_get_suspend_opp_freq(dev);
>> + atomic_set(&devfreq->suspend_count, 0);
>> +
>> dev_set_name(&devfreq->dev, "devfreq%d",
>> atomic_inc_return(&devfreq_no));
>> err = device_register(&devfreq->dev);
>> @@ -867,14 +874,28 @@ EXPORT_SYMBOL(devm_devfreq_remove_device);
>> */
>> int devfreq_suspend_device(struct devfreq *devfreq)
>> {
>> + int ret;
>> +
>> if (!devfreq)
>> return -EINVAL;
>>
>> - if (!devfreq->governor)
>> + if (atomic_inc_return(&devfreq->suspend_count) > 1)
>> return 0;
>>
>> - return devfreq->governor->event_handler(devfreq,
>> - DEVFREQ_GOV_SUSPEND, NULL);
>> + if (devfreq->governor) {
>> + ret = devfreq->governor->event_handler(devfreq,
>> + DEVFREQ_GOV_SUSPEND, NULL);
>> + if (ret)
>> + return ret;
>> + }
>> +
>> + if (devfreq->suspend_freq) {
>> + ret = devfreq_set_target(devfreq, devfreq->suspend_freq, 0);
>> + if (ret)
>> + return ret;
>> + }
>> +
>> + return 0;
>> }
>> EXPORT_SYMBOL(devfreq_suspend_device);
>>
>> @@ -888,14 +909,28 @@ EXPORT_SYMBOL(devfreq_suspend_device);
>> */
>> int devfreq_resume_device(struct devfreq *devfreq)
>> {
>> + int ret;
>> +
>> if (!devfreq)
>> return -EINVAL;
>>
>> - if (!devfreq->governor)
>> + if (atomic_dec_return(&devfreq->suspend_count) >= 1)
>> return 0;
>>
>> - return devfreq->governor->event_handler(devfreq,
>> - DEVFREQ_GOV_RESUME, NULL);
>> + if (devfreq->resume_freq) {
>> + ret = devfreq_set_target(devfreq, devfreq->resume_freq, 0);
>> + if (ret)
>> + return ret;
>> + }
>> +
>> + if (devfreq->governor) {
>> + ret = devfreq->governor->event_handler(devfreq,
>> + DEVFREQ_GOV_RESUME, NULL);
>> + if (ret)
>> + return ret;
>> + }
>> +
>> + return 0;
>> }
>> EXPORT_SYMBOL(devfreq_resume_device);
>>
>> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
>> index e4963b0..d985199 100644
>> --- a/include/linux/devfreq.h
>> +++ b/include/linux/devfreq.h
>> @@ -131,6 +131,9 @@ struct devfreq_dev_profile {
>> * @scaling_min_freq: Limit minimum frequency requested by OPP interface
>> * @scaling_max_freq: Limit maximum frequency requested by OPP interface
>> * @stop_polling: devfreq polling status of a device.
>> + * @suspend_freq: frequency of a device set during suspend phase.
>> + * @resume_freq: frequency of a device set in resume phase.
>> + * @suspend_count: suspend requests counter for a device.
>> * @total_trans: Number of devfreq transitions
>> * @trans_table: Statistics of devfreq transitions
>> * @time_in_state: Statistics of devfreq states
>> @@ -167,6 +170,10 @@ struct devfreq {
>> unsigned long scaling_max_freq;
>> bool stop_polling;
>>
>> + unsigned long suspend_freq;
>> + unsigned long resume_freq;
>> + atomic_t suspend_count;
>> +
>> /* information for device frequency transition */
>> unsigned int total_trans;
>> unsigned int *trans_table;
>>
>
>

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