linux-kernel - Re: [PATCH v2 3/3] devfreq: Add current freq callback in device profile

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Date:	Mon, 17 Sep 2012 10:34:54 +0000 (GMT)
From:	MyungJoo Ham <myungjoo.ham@...sung.com>
To:	Rajagopal Venkat <rajagopal.venkat@...aro.org>,
	"mturquette@...aro.org" <mturquette@...aro.org>,
	박경민 <kyungmin.park@...sung.com>,
	"rjw@...k.pl" <rjw@...k.pl>
Cc:	"patches@...aro.org" <patches@...aro.org>,
	"linaro-dev@...ts.linaro.org" <linaro-dev@...ts.linaro.org>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 3/3] devfreq: Add current freq callback in device profile

> From: Rajagopal Venkat <rajagopal.venkat@...aro.org>
> 
> Devfreq returns governor predicted frequency as current frequency
> via sysfs interface. But device may not support all frequencies
> that governor predicts. So add a callback in device profile to get
> current freq from driver. Also add a new sysfs node to expose
> governor predicted next target frequency.
> 
> Signed-off-by: Rajagopal Venkat <rajagopal.venkat@...aro.org>

Signed-off-by: MyungJoo Ham <myungjoo.ham@...sung.com>

> ---
>  Documentation/ABI/testing/sysfs-class-devfreq | 11 ++++++++++-
>  drivers/devfreq/devfreq.c                     | 14 ++++++++++++++
>  include/linux/devfreq.h                       |  3 +++
>  3 files changed, 27 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/ABI/testing/sysfs-class-devfreq b/Documentation/ABI/testing/sysfs-class-devfreq
> index 89283b1..e6cf08e 100644
> --- a/Documentation/ABI/testing/sysfs-class-devfreq
> +++ b/Documentation/ABI/testing/sysfs-class-devfreq
> @@ -19,7 +19,16 @@ Date:		September 2011
>  Contact:	MyungJoo Ham <myungjoo.ham@...sung.com>
>  Description:
>  		The /sys/class/devfreq/.../cur_freq shows the current
> -		frequency of the corresponding devfreq object.
> +		frequency of the corresponding devfreq object. Same as
> +		target_freq when get_cur_freq() is not implemented by
> +		devfreq driver.
> +
> +What:		/sys/class/devfreq/.../target_freq
> +Date:		September 2012
> +Contact:	Rajagopal Venkat <rajagopal.venkat@...aro.org>
> +Description:
> +		The /sys/class/devfreq/.../target_freq shows the next governor
> +		predicted target frequency of the corresponding devfreq object.
>  
>  What:		/sys/class/devfreq/.../polling_interval
>  Date:		September 2011
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 309c46e..049e273 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -401,6 +401,19 @@ static ssize_t show_governor(struct device *dev,
>  static ssize_t show_freq(struct device *dev,
>  			 struct device_attribute *attr, char *buf)
>  {
> +	unsigned long freq;
> +	struct devfreq *devfreq = to_devfreq(dev);
> +
> +	if (devfreq->profile->get_cur_freq &&
> +		!devfreq->profile->get_cur_freq(devfreq->dev.parent, &freq))
> +			return sprintf(buf, "%lu\n", freq);
> +
> +	return sprintf(buf, "%lu\n", devfreq->previous_freq);
> +}
> +
> +static ssize_t show_target_freq(struct device *dev,
> +			struct device_attribute *attr, char *buf)
> +{
>  	return sprintf(buf, "%lu\n", to_devfreq(dev)->previous_freq);
>  }
>  
> @@ -504,6 +517,7 @@ static ssize_t show_max_freq(struct device *dev, struct device_attribute *attr,
>  static struct device_attribute devfreq_attrs[] = {
>  	__ATTR(governor, S_IRUGO, show_governor, NULL),
>  	__ATTR(cur_freq, S_IRUGO, show_freq, NULL),
> +	__ATTR(target_freq, S_IRUGO, show_target_freq, NULL),
>  	__ATTR(polling_interval, S_IRUGO | S_IWUSR, show_polling_interval,
>  	       store_polling_interval),
>  	__ATTR(min_freq, S_IRUGO | S_IWUSR, show_min_freq, store_min_freq),
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index 7c7e179..d12ed41 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -66,6 +66,8 @@ struct devfreq_dev_status {
>   *			explained above with "DEVFREQ_FLAG_*" macros.
>   * @get_dev_status	The device should provide the current performance
>   *			status to devfreq, which is used by governors.
> + * @get_cur_freq	The device should provide the current frequency
> + *			at which it is operating.
>   * @exit		An optional callback that is called when devfreq
>   *			is removing the devfreq object due to error or
>   *			from devfreq_remove_device() call. If the user
> @@ -79,6 +81,7 @@ struct devfreq_dev_profile {
>  	int (*target)(struct device *dev, unsigned long *freq, u32 flags);
>  	int (*get_dev_status)(struct device *dev,
>  			      struct devfreq_dev_status *stat);
> +	int (*get_cur_freq)(struct device *dev, unsigned long *freq);
>  	void (*exit)(struct device *dev);
>  };
>  
> -- 
> 1.7.11.3
> 
> 
> 
> 
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