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Date: Thu, 15 Mar 2012 23:14:53 -0700
From: "Turquette, Mike" <mturquette@...com>
To: MyungJoo Ham <myungjoo.ham@...sung.com>
Cc: "Rafael J. Wysocki" <rjw@...k.pl>, 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 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>
> ---
> 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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