linux-kernel - Re: [PATCH 04/11] PM / devfreq: bail out early if no freq changes in devfreq_set

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Date:   Wed, 10 Mar 2021 00:47:39 +0900
From:   Chanwoo Choi <cwchoi00@...il.com>
To:     Dong Aisheng <aisheng.dong@....com>, linux-pm@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org
Cc:     dongas86@...il.com, kernel@...gutronix.de, shawnguo@...nel.org,
        linux-imx@....com, linux-kernel@...r.kernel.org,
        myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
        cw00.choi@...sung.com, abel.vesa@....com
Subject: Re: [PATCH 04/11] PM / devfreq: bail out early if no freq changes in
 devfreq_set_target

On 21. 3. 9. 오후 9:58, Dong Aisheng wrote:
> It's unnecessary to set the same freq again and run notifier calls.
> 
> Signed-off-by: Dong Aisheng <aisheng.dong@....com>
> ---
>   drivers/devfreq/devfreq.c | 5 ++++-
>   1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> index bf3047896e41..6e80bf70e7b3 100644
> --- a/drivers/devfreq/devfreq.c
> +++ b/drivers/devfreq/devfreq.c
> @@ -358,6 +358,9 @@ static int devfreq_set_target(struct devfreq *devfreq, unsigned long new_freq,
>   	else
>   		cur_freq = devfreq->previous_freq;
>   
> +	if (new_freq == cur_freq)
> +		return 0;
> +
>   	freqs.old = cur_freq;
>   	freqs.new = new_freq;
>   	devfreq_notify_transition(devfreq, &freqs, DEVFREQ_PRECHANGE);
> @@ -374,7 +377,7 @@ 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;
> 

I'd like you to squash patch4 with patch6 because actually patch6
is too minor clean-up. I think it is possible.

-- 
Best Regards,
Samsung Electronics
Chanwoo Choi