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    SubjectRe: [PATCH] PM / devfreq: add relation of recommended frequency.
    On Thu, Feb 9, 2012 at 11:19 PM, MyungJoo Ham <myungjoo.ham@samsung.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 options", does it.

    Nitpick: changelog still refers to "options" but code reads "flags".

    Regards,
    Mike

    >
    > With the update, devfreq_recommended_opp() is also updated.
    >
    > Signed-off-by: MyungJoo Ham <myungjoo.ham@samsung.com>
    > Signed-off-by: Kyungmin Park <kyungmin.park@samsung.com>
    > ---
    >  drivers/devfreq/devfreq.c     |   44 ++++++++++++++++++++++++++++++----------
    >  drivers/devfreq/exynos4_bus.c |   16 +++++++++++---
    >  include/linux/devfreq.h       |   18 ++++++++++++++--
    >  3 files changed, 60 insertions(+), 18 deletions(-)
    >
    > diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
    > index a33fc6c..83392a6 100644
    > --- a/drivers/devfreq/devfreq.c
    > +++ b/drivers/devfreq/devfreq.c
    > @@ -84,6 +84,7 @@ int update_devfreq(struct devfreq *devfreq)
    >  {
    >        unsigned long freq;
    >        int err = 0;
    > +       u32 options = 0;
    >
    >        if (!mutex_is_locked(&devfreq->lock)) {
    >                WARN(true, "devfreq->lock must be locked by the caller.\n");
    > @@ -104,18 +105,23 @@ int update_devfreq(struct devfreq *devfreq)
    >         * qos_min_freq
    >         */
    >
    > -       if (devfreq->qos_min_freq && freq < devfreq->qos_min_freq)
    > +       if (devfreq->qos_min_freq && freq < devfreq->qos_min_freq) {
    >                freq = devfreq->qos_min_freq;
    > -       if (devfreq->max_freq && freq > devfreq->max_freq)
    > +               options &= ~(1 << 0);
    > +               options |= DEVFREQ_OPTION_FREQ_LUB;
    > +       }
    > +       if (devfreq->max_freq && freq > devfreq->max_freq) {
    >                freq = devfreq->max_freq;
    > -       if (devfreq->min_freq && freq < devfreq->min_freq)
    > +               options &= ~(1 << 0);
    > +               options |= DEVFREQ_OPTION_FREQ_GLB;
    > +       }
    > +       if (devfreq->min_freq && freq < devfreq->min_freq) {
    >                freq = devfreq->min_freq;
    > +               options &= ~(1 << 0);
    > +               options |= DEVFREQ_OPTION_FREQ_LUB;
    > +       }
    >
    > -       /*
    > -        * TODO in the devfreq-next:
    > -        * add relation or use rance (freq_min, freq_max)
    > -        */
    > -       err = devfreq->profile->target(devfreq->dev.parent, &freq);
    > +       err = devfreq->profile->target(devfreq->dev.parent, &freq, options);
    >        if (err)
    >                return err;
    >
    > @@ -771,14 +777,30 @@ 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
    > + * @floor      false: find LUB first and use GLB if LUB not available.
    > + *             true:  find GLB first and use LUB if GLB not available.
    > + *
    > + * LUB: least upper bound (at least this freq or above, but the least)
    > + * GLB: greatest lower bound (at most this freq or below, but the most)
    >  *
    >  */
    > -struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq)
    > +struct opp *devfreq_recommended_opp(struct device *dev, unsigned long *freq,
    > +                                   bool floor)
    >  {
    > -       struct opp *opp = opp_find_freq_ceil(dev, freq);
    > +       struct opp *opp;
    >
    > -       if (opp == ERR_PTR(-ENODEV))
    > +       if (floor) {
    >                opp = opp_find_freq_floor(dev, freq);
    > +
    > +               if (opp == ERR_PTR(-ENODEV))
    > +                       opp = opp_find_freq_ceil(dev, freq);
    > +       } else {
    > +               opp = opp_find_freq_ceil(dev, freq);
    > +
    > +               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..c0a78da 100644
    > --- a/drivers/devfreq/exynos4_bus.c
    > +++ b/drivers/devfreq/exynos4_bus.c
    > @@ -619,13 +619,21 @@ 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 options)
    >  {
    >        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);
    > +       unsigned long def = *_freq;
    > +       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, options &
    > +                                                 DEVFREQ_OPTION_FREQ_GLB);
    >        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 b853379..1aff012 100644
    > --- a/include/linux/devfreq.h
    > +++ b/include/linux/devfreq.h
    > @@ -59,6 +59,16 @@ struct devfreq_pm_qos_table {
    >        s32 qos_value;
    >  };
    >
    > +/*
    > + * target callback, which is to provide additional information to the
    > + * devfreq driver.
    > + */
    > +
    > +/* The resulting frequency should be at least this. (least upper bound) */
    > +#define DEVFREQ_OPTION_FREQ_LUB        0x0
    > +/* The resulting frequency should be at most this. (greatest lower bound) */
    > +#define DEVFREQ_OPTION_FREQ_GLB 0x1
    > +
    >  /**
    >  * struct devfreq_dev_profile - Devfreq's user device profile
    >  * @initial_freq       The operating frequency when devfreq_add_device() is
    > @@ -76,6 +86,8 @@ struct devfreq_pm_qos_table {
    >  *                     higher than any operable frequency, set maximum.
    >  *                     Before returning, target function should set
    >  *                     freq at the current frequency.
    > + *                     The "option" parameter's possible values are
    > + *                     explained above with "DEVFREQ_OPTION_*" 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
    > @@ -95,7 +107,7 @@ struct devfreq_dev_profile {
    >        bool qos_use_max;
    >        struct devfreq_pm_qos_table *qos_list;
    >
    > -       int (*target)(struct device *dev, unsigned long *freq);
    > +       int (*target)(struct device *dev, unsigned long *freq, u32 options);
    >        int (*get_dev_status)(struct device *dev,
    >                              struct devfreq_dev_status *stat);
    >        void (*exit)(struct device *dev);
    > @@ -198,7 +210,7 @@ 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, bool floor);
    >  extern int devfreq_register_opp_notifier(struct device *dev,
    >                                         struct devfreq *devfreq);
    >  extern int devfreq_unregister_opp_notifier(struct device *dev,
    > @@ -253,7 +265,7 @@ static int devfreq_remove_device(struct devfreq *devfreq)
    >  }
    >
    >  static struct opp *devfreq_recommended_opp(struct device *dev,
    > -                                          unsigned long *freq)
    > +                                          unsigned long *freq, bool floor)
    >  {
    >        return -EINVAL;
    >  }
    > --
    > 1.7.4.1
    >
    --
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