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Date: Sat, 10 Mar 2012 22:51:10 +0100
From: "Rafael J. Wysocki" <rjw@...k.pl>
To: MyungJoo Ham <myungjoo.ham@...sung.com>
Cc: linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
Kyungmin Park <kyungmin.park@...sung.com>,
Kevin Hilman <khilman@...com>,
Mike Turquette <mturquette@...com>, myungjoo.ham@...il.com
Subject: Re: [PATCH] PM / devfreq: add relation of recommended frequency.
On Wednesday, March 07, 2012, MyungJoo Ham 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.
>
> With the update, devfreq_recommended_opp() is also updated.
>
> Signed-off-by: MyungJoo Ham <myungjoo.ham@...sung.com>
> Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
This one looks good.
Do you want me to take it as a patch, or to pull it from your tree?
Rafael
> ---
> Changes from v1
> - Style update.
> ---
> drivers/devfreq/devfreq.c | 41 ++++++++++++++++++++++++++++++-----------
> drivers/devfreq/exynos4_bus.c | 14 ++++++++++----
> include/linux/devfreq.h | 16 +++++++++++++---
> 3 files changed, 53 insertions(+), 18 deletions(-)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 0b49f59..13794d1 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 flags = 0;
>
> if (!mutex_is_locked(&devfreq->lock)) {
> WARN(true, "devfreq->lock must be locked by the caller.\n");
> @@ -104,18 +105,20 @@ 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)
> + flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
> + }
> + if (devfreq->max_freq && freq > devfreq->max_freq) {
> freq = devfreq->max_freq;
> - if (devfreq->min_freq && freq < devfreq->min_freq)
> + flags |= DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use LUB */
> + }
> + if (devfreq->min_freq && freq < devfreq->min_freq) {
> freq = devfreq->min_freq;
> + flags &= ~DEVFREQ_FLAG_LEAST_UPPER_BOUND; /* Use GLB */
> + }
>
> - /*
> - * 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, flags);
> if (err)
> return err;
>
> @@ -773,14 +776,30 @@ 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 f27d511..85d4b0f 100644
> --- a/include/linux/devfreq.h
> +++ b/include/linux/devfreq.h
> @@ -59,6 +59,14 @@ struct devfreq_pm_qos_table {
> s32 qos_value;
> };
>
> +/*
> + * 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
> @@ -74,6 +82,8 @@ struct devfreq_pm_qos_table {
> * higher than any operable frequency, set maximum.
> * Before returning, target function should set
> * freq at the current frequency.
> + * The "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
> @@ -92,7 +102,7 @@ struct devfreq_dev_profile {
> int qos_type;
> struct devfreq_pm_qos_table *qos_list;
>
> - 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);
> @@ -198,7 +208,7 @@ 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,
> @@ -253,7 +263,7 @@ 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;
> }
>
--
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