linux-kernel - Re: [PATCH v4 2/3] devfreq: Add suspend and resume apis

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Date:	Mon, 08 Oct 2012 00:01:40 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Rajagopal Venkat <rajagopal.venkat@...aro.org>
Cc:	myungjoo.ham@...sung.com, mturquette@...aro.org,
	kyungmin.park@...sung.com, patches@...aro.org,
	linaro-dev@...ts.linaro.org, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 2/3] devfreq: Add suspend and resume apis

On Thursday 04 of October 2012 14:58:33 Rajagopal Venkat wrote:
> Add devfreq suspend/resume apis for devfreq users. This patch
> supports suspend and resume of devfreq load monitoring, required
> for devices which can idle.
> 
> Signed-off-by: Rajagopal Venkat <rajagopal.venkat@...aro.org>
> Acked-by: MyungJoo Ham <myungjoo.ham@...sung.com>

Well, I wonder if this may be tied in to the runtime PM framework, so that,
for example, pm_runtime_suspend() will automatically suspend devfreq on
success (and the runtime resume of the device will resume devfreq)?

Rafael


> ---
>  drivers/devfreq/devfreq.c                 | 28 ++++++++++++++++++++++++++++
>  drivers/devfreq/governor.h                |  2 ++
>  drivers/devfreq/governor_simpleondemand.c |  9 +++++++++
>  include/linux/devfreq.h                   | 12 ++++++++++++
>  4 files changed, 51 insertions(+)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 41a4099..63e075e 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -428,6 +428,34 @@ int devfreq_remove_device(struct devfreq *devfreq)
>  }
>  EXPORT_SYMBOL(devfreq_remove_device);
>  
> +/**
> + * devfreq_suspend_device() - Suspend devfreq of a device.
> + * @devfreq	the devfreq instance to be suspended
> + */
> +int devfreq_suspend_device(struct devfreq *devfreq)
> +{
> +	if (!devfreq)
> +		return -EINVAL;
> +
> +	return devfreq->governor->event_handler(devfreq,
> +				DEVFREQ_GOV_SUSPEND, NULL);
> +}
> +EXPORT_SYMBOL(devfreq_suspend_device);
> +
> +/**
> + * devfreq_resume_device() - Resume devfreq of a device.
> + * @devfreq	the devfreq instance to be resumed
> + */
> +int devfreq_resume_device(struct devfreq *devfreq)
> +{
> +	if (!devfreq)
> +		return -EINVAL;
> +
> +	return devfreq->governor->event_handler(devfreq,
> +				DEVFREQ_GOV_RESUME, NULL);
> +}
> +EXPORT_SYMBOL(devfreq_resume_device);
> +
>  static ssize_t show_governor(struct device *dev,
>  			     struct device_attribute *attr, char *buf)
>  {
> diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
> index bb3aff3..26432ac 100644
> --- a/drivers/devfreq/governor.h
> +++ b/drivers/devfreq/governor.h
> @@ -22,6 +22,8 @@
>  #define DEVFREQ_GOV_START			0x1
>  #define DEVFREQ_GOV_STOP			0x2
>  #define DEVFREQ_GOV_INTERVAL			0x3
> +#define DEVFREQ_GOV_SUSPEND			0x4
> +#define DEVFREQ_GOV_RESUME			0x5
>  
>  /* Caution: devfreq->lock must be locked before calling update_devfreq */
>  extern int update_devfreq(struct devfreq *devfreq);
> diff --git a/drivers/devfreq/governor_simpleondemand.c b/drivers/devfreq/governor_simpleondemand.c
> index cf94218..a8ba78c 100644
> --- a/drivers/devfreq/governor_simpleondemand.c
> +++ b/drivers/devfreq/governor_simpleondemand.c
> @@ -104,6 +104,15 @@ int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
>  	case DEVFREQ_GOV_INTERVAL:
>  		devfreq_interval_update(devfreq, (unsigned int *)data);
>  		break;
> +
> +	case DEVFREQ_GOV_SUSPEND:
> +		devfreq_monitor_suspend(devfreq);
> +		break;
> +
> +	case DEVFREQ_GOV_RESUME:
> +		devfreq_monitor_resume(devfreq);
> +		break;
> +
>  	default:
>  		break;
>  	}
> diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> index 9cdffde..ee243a3 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -158,6 +158,8 @@ extern struct devfreq *devfreq_add_device(struct device *dev,
>  				  const struct devfreq_governor *governor,
>  				  void *data);
>  extern int devfreq_remove_device(struct devfreq *devfreq);
> +extern int devfreq_suspend_device(struct devfreq *devfreq);
> +extern int devfreq_resume_device(struct devfreq *devfreq);
>  
>  /* Helper functions for devfreq user device driver with OPP. */
>  extern struct opp *devfreq_recommended_opp(struct device *dev,
> @@ -211,6 +213,16 @@ static int devfreq_remove_device(struct devfreq *devfreq)
>  	return 0;
>  }
>  
> +static int devfreq_suspend_device(struct devfreq *devfreq)
> +{
> +	return 0;
> +}
> +
> +static int devfreq_resume_device(struct devfreq *devfreq)
> +{
> +	return 0;
> +}
> +
>  static struct opp *devfreq_recommended_opp(struct device *dev,
>  					   unsigned long *freq, u32 flags)
>  {
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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