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SubjectRe: [PATCH] PM / devfreq: Remove redundant frequency adjustment from governors
Hi,

On 2018년 05월 17일 06:10, Matthias Kaehlcke wrote:
> The performance, powersave, simpleondemand and userspace governors
> determine a target frequency and then adjust it according to the
> df->min/max_freq limits that might have been set by user space. This
> adjustment is redundant, it is done in update_devfreq() for any
> governor, right after governor->get_target_freq().
>
> Signed-off-by: Matthias Kaehlcke <mka@chromium.org>
> ---
> drivers/devfreq/governor_performance.c | 10 ++--------
> drivers/devfreq/governor_powersave.c | 5 -----
> drivers/devfreq/governor_simpleondemand.c | 7 +------
> drivers/devfreq/governor_userspace.c | 16 ++++------------
> 4 files changed, 7 insertions(+), 31 deletions(-)
>
> diff --git a/drivers/devfreq/governor_performance.c b/drivers/devfreq/governor_performance.c
> index 4d23ecfbd948..31ee30622c00 100644
> --- a/drivers/devfreq/governor_performance.c
> +++ b/drivers/devfreq/governor_performance.c
> @@ -16,14 +16,8 @@
> static int devfreq_performance_func(struct devfreq *df,
> unsigned long *freq)
> {
> - /*
> - * target callback should be able to get floor value as
> - * said in devfreq.h
> - */
> - if (!df->max_freq)
> - *freq = UINT_MAX;
> - else
> - *freq = df->max_freq;
> + *freq = UINT_MAX;
> +

It is difficult to understand why use UINT_MAX instead of df->max_freq.

Instead, after merged the commit ab8f58ad72c4 ("PM / devfreq: Set min/max_freq
when adding the devfreq device"), df->max/min_freq have the specific frequency
value always. So, we can change it as following without UINT_MAX.

*freq = df->max_freq;


> return 0;
> }
>
> diff --git a/drivers/devfreq/governor_powersave.c b/drivers/devfreq/governor_powersave.c
> index 0c42f23249ef..50a891f7c92d 100644
> --- a/drivers/devfreq/governor_powersave.c
> +++ b/drivers/devfreq/governor_powersave.c
> @@ -16,11 +16,6 @@
> static int devfreq_powersave_func(struct devfreq *df,
> unsigned long *freq)
> {
> - /*
> - * target callback should be able to get ceiling value as
> - * said in devfreq.h
> - */
> - *freq = df->min_freq;
> return 0;

Each function have to keep their own function role.
Please keep '*freq = df->min_freq'.

> }
>
> diff --git a/drivers/devfreq/governor_simpleondemand.c b/drivers/devfreq/governor_simpleondemand.c
> index 28e0f2de7100..7ed733c528f4 100644
> --- a/drivers/devfreq/governor_simpleondemand.c
> +++ b/drivers/devfreq/governor_simpleondemand.c
> @@ -27,7 +27,7 @@ static int devfreq_simple_ondemand_func(struct devfreq *df,
> unsigned int dfso_upthreshold = DFSO_UPTHRESHOLD;
> unsigned int dfso_downdifferential = DFSO_DOWNDIFFERENCTIAL;
> struct devfreq_simple_ondemand_data *data = df->data;
> - unsigned long max = (df->max_freq) ? df->max_freq : UINT_MAX;
> + unsigned long max = UINT_MAX;

Use df->max_freq instead of UINT_MAX as following.

unsigned long max = df->max_freq;

>
> err = devfreq_update_stats(df);
> if (err)
> @@ -85,11 +85,6 @@ static int devfreq_simple_ondemand_func(struct devfreq *df,
> b = div_u64(b, (dfso_upthreshold - dfso_downdifferential / 2));
> *freq = (unsigned long) b;
>
> - if (df->min_freq && *freq < df->min_freq)
> - *freq = df->min_freq;
> - if (df->max_freq && *freq > df->max_freq)
> - *freq = df->max_freq;
> -
> return 0;
> }
>
> diff --git a/drivers/devfreq/governor_userspace.c b/drivers/devfreq/governor_userspace.c
> index 080607c3f34d..378d84c011df 100644
> --- a/drivers/devfreq/governor_userspace.c
> +++ b/drivers/devfreq/governor_userspace.c
> @@ -26,19 +26,11 @@ static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq)
> {
> struct userspace_data *data = df->data;
>
> - if (data->valid) {
> - unsigned long adjusted_freq = data->user_frequency;
> -
> - if (df->max_freq && adjusted_freq > df->max_freq)
> - adjusted_freq = df->max_freq;
> -
> - if (df->min_freq && adjusted_freq < df->min_freq)
> - adjusted_freq = df->min_freq;
> -
> - *freq = adjusted_freq;
> - } else {
> + if (data->valid)
> + *freq = data->user_frequency;
> + else
> *freq = df->previous_freq; /* No user freq specified yet */
> - }
> +
> return 0;
> }
>
>


--
Best Regards,
Chanwoo Choi
Samsung Electronics

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