Re: [PATCH V2 RESEND 3/4] PM / devfreq: bail out early if no freq changes in devfreq_set_target
From: Chanwoo Choi <hidden>
Date: 2021-03-23 15:02:55
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linux-pm, lkml
On 21. 3. 23. 오후 4:20, Dong Aisheng wrote:
quoted hunk ↗ jump to hunk
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.
quoted hunk ↗ jump to hunk
+ 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 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel