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Message-Id: <201203162207.22818.rjw@sisk.pl>
Date: Fri, 16 Mar 2012 22:07:22 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: "Turquette, Mike" <mturquette@...com>
Cc: MyungJoo Ham <myungjoo.ham@...sung.com>, linux-pm@...r.kernel.org,
linux-kernel@...r.kernel.org,
Kyungmin Park <kyungmin.park@...sung.com>,
Kevin Hilman <khilman@...com>, myungjoo.ham@...il.com
Subject: Re: [PATCH v3] PM / devfreq: add relation of recommended frequency.
On Friday, March 16, 2012, Turquette, Mike wrote:
> On Thu, Mar 15, 2012 at 11:02 PM, MyungJoo Ham <myungjoo.ham@...sung.com> wrote:
> > The semantics of "target frequency" given to devfreq driver from
> > devfreq framework has always been interpretted as "at least" or GLB
> > (greatest lower bound). However, the framework might want the
> > device driver to limit its max frequency (LUB: least upper bound),
> > especially if it is given by thermal framework (it's too hot).
> >
> > Thus, the target fuction should have another parameter to express
> > whether the framework wants GLB or LUB. And, the additional parameter,
> > "u32 flags", does it.
> >
> > With the update, devfreq_recommended_opp() is also updated.
> >
> > Signed-off-by: MyungJoo Ham <myungjoo.ham@...sung.com>
>
> I know Rafael already said he'd take it but I might as well add:
>
> Reviewed-by: Mike Turquette <mturquette@...com>
>
> > Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
Applied to linux-pm/linux-next.
Thanks,
Rafael
> > ---
> > Changes from v2
> > - Updated comments
> > - Rebased.
> >
> > Changes from v1
> > - Style update.
> >
> > drivers/devfreq/devfreq.c | 42 +++++++++++++++++++++++++++++++++++++---
> > drivers/devfreq/exynos4_bus.c | 14 +++++++++---
> > include/linux/devfreq.h | 16 ++++++++++++--
> > 3 files changed, 61 insertions(+), 11 deletions(-)
> >
> > diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> > index a129a7b..70c31d4 100644
> > --- a/drivers/devfreq/devfreq.c
> > +++ b/drivers/devfreq/devfreq.c
> > @@ -83,6 +83,7 @@ int update_devfreq(struct devfreq *devfreq)
> > {
> > unsigned long freq;
> > int err = 0;
> > + u32 flags = 0;
> >
> > if (!mutex_is_locked(&devfreq->lock)) {
> > WARN(true, "devfreq->lock must be locked by the caller.\n");
> > @@ -94,7 +95,24 @@ int update_devfreq(struct devfreq *devfreq)
> > if (err)
> > return err;
> >
> > - err = devfreq->profile->target(devfreq->dev.parent, &freq);
> > + /*
> > + * Adjust the freuqency with user freq and QoS.
> > + *
> > + * List from the highest proiority
> > + * max_freq (probably called by thermal when it's too hot)
> > + * min_freq
> > + */
> > +
> > + if (devfreq->min_freq && freq < devfreq->min_freq) {
> > + freq = devfreq->min_freq;
> > + flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
> > + }
> > + if (devfreq->max_freq && freq > devfreq->max_freq) {
> > + freq = devfreq->max_freq;
> > + flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
> > + }
> > +
> > + err = devfreq->profile->target(devfreq->dev.parent, &freq, flags);
> > if (err)
> > return err;
> >
> > @@ -625,14 +643,30 @@ module_exit(devfreq_exit);
> > * freq value given to target callback.
> > * @dev The devfreq user device. (parent of devfreq)
> > * @freq The frequency given to target function
> > + * @flags Flags handed from devfreq framework.
> > *
> > */
> > -struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq)
> > +struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq,
> > + u32 flags)
> > {
> > - struct opp *opp = opp_find_freq_ceil(dev, freq);
> > + struct opp *opp;
> >
> > - if (opp == ERR_PTR(-ENODEV))
> > + if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
> > + /* The freq is an upper bound. opp should be lower */
> > opp = opp_find_freq_floor(dev, freq);
> > +
> > + /* If not available, use the closest opp */
> > + if (opp == ERR_PTR(-ENODEV))
> > + opp = opp_find_freq_ceil(dev, freq);
> > + } else {
> > + /* The freq is an lower bound. opp should be higher */
> > + opp = opp_find_freq_ceil(dev, freq);
> > +
> > + /* If not available, use the closest opp */
> > + if (opp == ERR_PTR(-ENODEV))
> > + opp = opp_find_freq_floor(dev, freq);
> > + }
> > +
> > return opp;
> > }
> >
> > diff --git a/drivers/devfreq/exynos4_bus.c b/drivers/devfreq/exynos4_bus.c
> > index 590d686..1a361e9 100644
> > --- a/drivers/devfreq/exynos4_bus.c
> > +++ b/drivers/devfreq/exynos4_bus.c
> > @@ -619,13 +619,19 @@ static int exynos4_bus_setvolt(struct busfreq_data *data, struct opp *opp,
> > return err;
> > }
> >
> > -static int exynos4_bus_target(struct device *dev, unsigned long *_freq)
> > +static int exynos4_bus_target(struct device *dev, unsigned long *_freq,
> > + u32 flags)
> > {
> > int err = 0;
> > - struct busfreq_data *data = dev_get_drvdata(dev);
> > - struct opp *opp = devfreq_recommended_opp(dev, _freq);
> > - unsigned long old_freq = opp_get_freq(data->curr_opp);
> > + struct platform_device *pdev = container_of(dev, struct platform_device,
> > + dev);
> > + struct busfreq_data *data = platform_get_drvdata(pdev);
> > + struct opp *opp = devfreq_recommended_opp(dev, _freq, flags);
> > unsigned long freq = opp_get_freq(opp);
> > + unsigned long old_freq = opp_get_freq(data->curr_opp);
> > +
> > + if (IS_ERR(opp))
> > + return PTR_ERR(opp);
> >
> > if (old_freq == freq)
> > return 0;
> > diff --git a/include/linux/devfreq.h b/include/linux/devfreq.h
> > index 5862475..281c72a 100644
> > --- a/include/linux/devfreq.h
> > +++ b/include/linux/devfreq.h
> > @@ -44,6 +44,14 @@ struct devfreq_dev_status {
> > void *private_data;
> > };
> >
> > +/*
> > + * The resulting frequency should be at most this. (this bound is the
> > + * least upper bound; thus, the resulting freq should be lower or same)
> > + * If the flag is not set, the resulting frequency should be at most the
> > + * bound (greatest lower bound)
> > + */
> > +#define DEVFREQ_FLAG_LEAST_UPPER_BOUND 0x1
> > +
> > /**
> > * struct devfreq_dev_profile - Devfreq's user device profile
> > * @initial_freq The operating frequency when devfreq_add_device() is
> > @@ -54,6 +62,8 @@ struct devfreq_dev_status {
> > * higher than any operable frequency, set maximum.
> > * Before returning, target function should set
> > * freq at the current frequency.
> > + * The "flags" parameter's possible values are
> > + * explained above with "DEVFREQ_FLAG_*" macros.
> > * @get_dev_status The device should provide the current performance
> > * status to devfreq, which is used by governors.
> > * @exit An optional callback that is called when devfreq
> > @@ -66,7 +76,7 @@ struct devfreq_dev_profile {
> > unsigned long initial_freq;
> > unsigned int polling_ms;
> >
> > - int (*target)(struct device *dev, unsigned long *freq);
> > + int (*target)(struct device *dev, unsigned long *freq, u32 flags);
> > int (*get_dev_status)(struct device *dev,
> > struct devfreq_dev_status *stat);
> > void (*exit)(struct device *dev);
> > @@ -165,7 +175,7 @@ extern int devfreq_remove_device(struct devfreq *devfreq);
> >
> > /* Helper functions for devfreq user device driver with OPP. */
> > extern struct opp *devfreq_recommended_opp(struct device *dev,
> > - unsigned long *freq);
> > + unsigned long *freq, u32 flags);
> > extern int devfreq_register_opp_notifier(struct device *dev,
> > struct devfreq *devfreq);
> > extern int devfreq_unregister_opp_notifier(struct device *dev,
> > @@ -216,7 +226,7 @@ static int devfreq_remove_device(struct devfreq *devfreq)
> > }
> >
> > static struct opp *devfreq_recommended_opp(struct device *dev,
> > - unsigned long *freq)
> > + unsigned long *freq, u32 flags)
> > {
> > return -EINVAL;
> > }
> > --
> > 1.7.4.1
> >
>
>
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