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Subject: Re: [PATCH v2 4/4] PM / devfreq: Add required OPPs support to
 passive governor
To:     Saravana Kannan <saravanak@google.com>,
        MyungJoo Ham <myungjoo.ham@samsung.com>,
        Kyungmin Park <kyungmin.park@samsung.com>,
        Viresh Kumar <vireshk@kernel.org>, Nishanth Menon <nm@ti.com>,
        Stephen Boyd <sboyd@kernel.org>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc:     kernel-team@android.com, linux-pm@vger.kernel.org,
        linux-kernel@vger.kernel.org,
        "cpgs (cpgs@samsung.com)" <cpgs@samsung.com>
From:   Chanwoo Choi <cw00.choi@samsung.com>
Organization: Samsung Electronics
Message-ID: <0d552b60-8ef1-5d66-d8bf-c192c15c325f@samsung.com>
Date:   Wed, 26 Jun 2019 10:59:16 +0900
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References: <20190625213337.157525-1-saravanak@google.com>
        <CGME20190625213400epcas5p417a68ce8bc5e097e4363fd61bd0a667f@epcas5p4.samsung.com>
        <20190625213337.157525-5-saravanak@google.com>
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Hi Saravana,

On 19. 6. 26. 오전 6:33, Saravana Kannan wrote:
> Look at the required OPPs of the "parent" device to determine the OPP that
> is required from the slave device managed by the passive governor. This
> allows having mappings between a parent device and a slave device even when
> they don't have the same number of OPPs.
> 
> Signed-off-by: Saravana Kannan <saravanak@google.com>
> ---
>  drivers/devfreq/governor_passive.c | 20 +++++++++++++++-----
>  1 file changed, 15 insertions(+), 5 deletions(-)
> 
> diff --git a/drivers/devfreq/governor_passive.c b/drivers/devfreq/governor_passive.c
> index 3bc29acbd54e..f6de03de7a64 100644
> --- a/drivers/devfreq/governor_passive.c
> +++ b/drivers/devfreq/governor_passive.c
> @@ -22,7 +22,7 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>  			= (struct devfreq_passive_data *)devfreq->data;
>  	struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent;
>  	unsigned long child_freq = ULONG_MAX;
> -	struct dev_pm_opp *opp;
> +	struct dev_pm_opp *opp = NULL, *p_opp = NULL;
>  	int i, count, ret = 0;
>  
>  	/*
> @@ -59,13 +59,20 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>  	 * list of parent device. Because in this case, *freq is temporary
>  	 * value which is decided by ondemand governor.
>  	 */
> -	opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, 0);
> -	if (IS_ERR(opp)) {
> -		ret = PTR_ERR(opp);
> +	p_opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, 0);
> +	if (IS_ERR(p_opp)) {
> +		ret = PTR_ERR(p_opp);
>  		goto out;
>  	}
>  
> -	dev_pm_opp_put(opp);
> +	if (devfreq->opp_table && parent_devfreq->opp_table)
> +		opp = dev_pm_opp_xlate_opp(parent_devfreq->opp_table,
> +					   devfreq->opp_table, p_opp);
> +	if (opp) {
> +		*freq = dev_pm_opp_get_freq(opp);
> +		dev_pm_opp_put(opp);
> +		goto out;
> +	}
>  
>  	/*
>  	 * Get the OPP table's index of decided freqeuncy by governor
> @@ -92,6 +99,9 @@ static int devfreq_passive_get_target_freq(struct devfreq *devfreq,
>  	*freq = child_freq;
>  
>  out:
> +	if (!IS_ERR_OR_NULL(opp))
> +		dev_pm_opp_put(p_opp);
> +
>  	return ret;
>  }
>  
> 

I agree this approach. It is necessary.
Acked-by: Chanwoo Choi <cw00.choi@samsung.com>


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics