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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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