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Date: Mon, 08 Oct 2012 10:48:27 +0000 (GMT)
From: MyungJoo Ham <myungjoo.ham@...sung.com>
To: Rajagopal Venkat <rajagopal.venkat@...aro.org>,
"Rafael J. Wysocki" <rjw@...k.pl>
Cc: "mturquette@...aro.org" <mturquette@...aro.org>,
¹Ú°æ¹Î <kyungmin.park@...sung.com>,
"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: Re: [PATCH v4 2/3] devfreq: Add suspend and resume apis
> On 8 October 2012 03:31, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > 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)?
>
> That's a good idea. If you agree, we can handle this as separate patch on
> top this patchset.
I guess implementing the idea may be not so obvious; thus, seperating
the patchset would be appropriate.
When we implement the idea, we may need to implement at the
pm_runtime core. Because devfreq->dev is a child of the target dev, not
a parent, runtime-pm event of the target dev does not automatically
invoke a cascaded action on the devfreq->dev.
Maybe either
1) capability to allow a child to monitor the power state of a parent
(I remember Inki Dae once suggested to add notifiers at runtime-pm, but
it seems to be not merged)
or
2) letting runtime-pm be aware of devfreq
(doesn't feel alright with this??)
is required?
>
> >
> > 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.
>
>
>
> --
> Regards,
> Rajagopal
>
>
>
>
>
>
>
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