From: Chanwoo Choi <cwchoi00@gmail.com>
To: Dong Aisheng <aisheng.dong@nxp.com>,
linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org
Cc: dongas86@gmail.com, kernel@pengutronix.de, shawnguo@kernel.org,
linux-imx@nxp.com, linux-kernel@vger.kernel.org,
myungjoo.ham@samsung.com, kyungmin.park@samsung.com,
cw00.choi@samsung.com, abel.vesa@nxp.com
Subject: Re: [PATCH V2 RESEND 3/4] PM / devfreq: bail out early if no freq changes in devfreq_set_target
Date: Wed, 24 Mar 2021 00:01:52 +0900 [thread overview]
Message-ID: <3054611c-4f43-8432-bd14-1733ab82804b@gmail.com> (raw)
In-Reply-To: <1616484011-26702-4-git-send-email-aisheng.dong@nxp.com>
On 21. 3. 23. 오후 4:20, Dong Aisheng wrote:
> It's unnecessary to set the same freq again and run notifier calls.
>
> Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
> ---
> drivers/devfreq/devfreq.c | 9 ++++++---
> 1 file changed, 6 insertions(+), 3 deletions(-)
>
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index 85927bd7ee76..a6ee91dd17bd 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -352,13 +352,16 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
> {
> struct devfreq_freqs freqs;
> unsigned long cur_freq;
> - int err = 0;
> + int err;
>
> if (devfreq->profile->get_cur_freq)
> devfreq->profile->get_cur_freq(devfreq->dev.parent, &cur_freq);
> else
> cur_freq = devfreq->previous_freq;
>
> + if (new_freq == cur_freq)
> + return 0;
cur_freq is one of the OPP frequencies. But, new_freq is calculated from
governor algorithm. It means that new_freq is not one of the
frequencies. Actually, it is not efficient.
After devfreq->profile->target() which almost uses
devfreq_recommended_opp(), new_freq is one of OPP frequencies.
> +
> freqs.old = cur_freq;
> freqs.new = new_freq;
> devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
> @@ -375,7 +378,7 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
> * and DEVFREQ_POSTCHANGE because for showing the correct frequency
> * change order of between devfreq device and passive devfreq device.
> */
> - if (trace_devfreq_frequency_enabled() && new_freq != cur_freq)
> + if (trace_devfreq_frequency_enabled())
> trace_devfreq_frequency(devfreq, new_freq, cur_freq);
>
> freqs.new = new_freq;
> @@ -390,7 +393,7 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
> if (devfreq->suspend_freq)
> devfreq->resume_freq = new_freq;
>
> - return err;
> + return 0;
> }
>
> /**
>
--
Best Regards,
Samsung Electronics
Chanwoo Choi
next prev parent reply other threads:[~2021-03-23 15:02 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-23 7:20 [PATCH V2 RESEND 0/4] PM / devfreq: a few small fixes and improvements Dong Aisheng
2021-03-23 7:20 ` [PATCH V2 RESEND 1/4] PM / devfreq: Use more accurate returned new_freq as resume_freq Dong Aisheng
2021-03-23 14:55 ` Chanwoo Choi
2021-03-23 7:20 ` [PATCH V2 RESEND 2/4] PM / devfreq: Remove the invalid description for get_target_freq Dong Aisheng
2021-03-23 14:56 ` Chanwoo Choi
2021-03-23 7:20 ` [PATCH V2 RESEND 3/4] PM / devfreq: bail out early if no freq changes in devfreq_set_target Dong Aisheng
2021-03-23 15:01 ` Chanwoo Choi [this message]
2021-05-19 6:51 ` Dong Aisheng
2021-03-23 7:20 ` [PATCH V2 RESEND 4/4] PM / devfreq: imx8m-ddrc: remove imx8m_ddrc_get_dev_status Dong Aisheng
2021-03-23 14:56 ` Chanwoo Choi
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