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Subject: Re: [PATCH 08/11] PM / devfreq: check get_dev_status in
 devfreq_update_stats
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
References: <1615294733-22761-1-git-send-email-aisheng.dong@nxp.com>
 <1615294733-22761-9-git-send-email-aisheng.dong@nxp.com>
From:   Chanwoo Choi <cwchoi00@gmail.com>
Message-ID: <0b6ceb75-040f-8e1c-73ea-9d60344b9918@gmail.com>
Date:   Wed, 10 Mar 2021 01:20:12 +0900
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On 21. 3. 9. 오후 9:58, Dong Aisheng wrote:
> Check .get_dev_status() in devfreq_update_stats in case it's abused
> when a device does not provide it.
> 
> Signed-off-by: Dong Aisheng <aisheng.dong@nxp.com>
> ---
>   drivers/devfreq/governor.h | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/devfreq/governor.h b/drivers/devfreq/governor.h
> index 31af6d072a10..67a6dbdd5d23 100644
> --- a/drivers/devfreq/governor.h
> +++ b/drivers/devfreq/governor.h
> @@ -89,6 +89,9 @@ int devfreq_update_target(struct devfreq *devfreq, unsigned long freq);
>   
>   static inline int devfreq_update_stats(struct devfreq *df)
>   {
> +	if (!df->profile->get_dev_status)
> +		return -EINVAL;
> +

I'm considering the following method instead of returning the error
when .get_dev_status is NULL.

	if (!df->profile->get_dev_status) {
		df->last_status.total_time = 0;
		df->last_status.busy_time = 0;
		df->last_status.current_frequency = 0;
		return 0;	
	}	

>   	return df->profile->get_dev_status(df->dev.parent, &df->last_status);
>   }
>   #endif /* _GOVERNOR_H */
> 


-- 
Best Regards,
Samsung Electronics
Chanwoo Choi