linux-kernel - Re: [PATCH v2 3/5] devfreq: add devfreq

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Message-id: <5C061C74.808@samsung.com>
Date:   Tue, 04 Dec 2018 15:19:32 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Lukasz Luba <l.luba@...tner.samsung.com>,
        linux-arm-kernel@...ts.infradead.org,
        linux-samsung-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, devicetree@...r.kernel.org
Cc:     tjakobi@...h.uni-bielefeld.de, myungjoo.ham@...sung.com,
        kyungmin.park@...sung.com, rjw@...ysocki.net, len.brown@...el.com,
        pavel@....cz, gregkh@...uxfoundation.org, keescook@...omium.org,
        anton@...msg.org, ccross@...roid.com, tony.luck@...el.com,
        robh+dt@...nel.org, mark.rutland@....com, kgene@...nel.org,
        krzk@...nel.org, m.szyprowski@...sung.com, b.zolnierkie@...sung.com
Subject: Re: [PATCH v2 3/5] devfreq: add devfreq_suspend/resume() functions

Hi Lukasz,

On 2018년 12월 03일 23:31, Lukasz Luba wrote:
> This patch adds implementation for global suspend/resume for
> devfreq framework. System suspend will next use these functions.
> 
> The patch is based on earlier work by Tobias Jakobi.

Please remove it from each patch description.

> 
> Suggested-by: Tobias Jakobi <tjakobi@...h.uni-bielefeld.de>
> Suggested-by: Chanwoo Choi <cw00.choi@...sung.com>
> Signed-off-by: Lukasz Luba <l.luba@...tner.samsung.com>
> ---
>  drivers/devfreq/devfreq.c | 42 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/devfreq.h   |  6 ++++++
>  2 files changed, 48 insertions(+)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 36bed24..7d60423 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -935,6 +935,48 @@ int devfreq_resume_device(struct devfreq *devfreq)
>  EXPORT_SYMBOL(devfreq_resume_device);
>  
>  /**
> + * devfreq_suspend() - Suspend devfreq governors and devices
> + *
> + * Called during system wide Suspend/Hibernate cycles for suspending governors
> + * and devices preserving the state for resume. On some platforms the devfreq
> + * device must have precise state (frequency) after resume in order to provide
> + * fully operating setup.
> + */
> +void devfreq_suspend(void)
> +{
> +	struct devfreq *devfreq;
> +	int ret;
> +
> +	mutex_lock(&devfreq_list_lock);
> +	list_for_each_entry(devfreq, &devfreq_list, node) {
> +		ret = devfreq_suspend_device(devfreq);
> +		if (ret)
> +			dev_warn(&devfreq->dev, "device suspend failed\n");

When I checked the cpufreq_suspend(), cpufreq_suspend() prints message as 'err' level.
I think that dev_err is more proper than dev_warn.

I'm not sure what is more correct log.
But, 'devfreq->dev' device has the separate suspend/resume function.
So, I think that devfreq_suspend() should print error log containing
that it is error by devfreq framework.

"device suspend failed"
-> "failed to suspend devfreq device"

> +	}
> +	mutex_unlock(&devfreq_list_lock);
> +}
> +
> +/**
> + * devfreq_resume() - Resume devfreq governors and devices
> + *
> + * Called during system wide Suspend/Hibernate cycle for resuming governors and
> + * devices that are suspended with devfreq_suspend().
> + */
> +void devfreq_resume(void)
> +{
> +	struct devfreq *devfreq;
> +	int ret;
> +
> +	mutex_lock(&devfreq_list_lock);
> +	list_for_each_entry(devfreq, &devfreq_list, node) {
> +		ret = devfreq_resume_device(devfreq);
> +		if (ret)
> +			dev_warn(&devfreq->dev, "device resume failed\n");

ditto.

"device resume failed"
-> "failed to resume devfreq device"


> +	}
> +	mutex_unlock(&devfreq_list_lock);
> +}
> +
> +/**
>   * devfreq_add_governor() - Add devfreq governor
>   * @governor:	the devfreq governor to be added
>   */
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index d985199..fbffa74 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -205,6 +205,9 @@ extern void devm_devfreq_remove_device(struct device *dev,
>  extern int devfreq_suspend_device(struct devfreq *devfreq);
>  extern int devfreq_resume_device(struct devfreq *devfreq);
>  
> +extern void devfreq_suspend(void);
> +extern void devfreq_resume(void);
> +
>  /**
>   * update_devfreq() - Reevaluate the device and configure frequency
>   * @devfreq:	the devfreq device
> @@ -331,6 +334,9 @@ static inline int devfreq_resume_device(struct devfreq *devfreq)
>  	return 0;
>  }
>  
> +static inline void devfreq_suspend(void) {}
> +static inline void devfreq_resume(void) {}
> +
>  static inline struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
>  					   unsigned long *freq, u32 flags)
>  {
> 

-- 
Best Regards,
Chanwoo Choi
Samsung Electronics