linux-kernel - Re: [PATCH v2 09/15] PM / devfreq: Switch to dev_pm_opp_find_freq_{ceil/floor}

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Date:   Mon, 24 Jul 2023 11:16:11 +0530
From:   Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
To:     Chanwoo Choi <chanwoo@...nel.org>
Cc:     vireshk@...nel.org, nm@...com, sboyd@...nel.org,
        myungjoo.ham@...sung.com, kyungmin.park@...sung.com,
        cw00.choi@...sung.com, andersson@...nel.org,
        konrad.dybcio@...aro.org, robh+dt@...nel.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        jejb@...ux.ibm.com, martin.petersen@...cle.com,
        alim.akhtar@...sung.com, avri.altman@....com, bvanassche@....org,
        linux-scsi@...r.kernel.org, linux-pm@...r.kernel.org,
        linux-arm-msm@...r.kernel.org, devicetree@...r.kernel.org,
        quic_asutoshd@...cinc.com, quic_cang@...cinc.com,
        quic_nitirawa@...cinc.com, quic_narepall@...cinc.com,
        quic_bhaskarv@...cinc.com, quic_richardp@...cinc.com,
        quic_nguyenb@...cinc.com, quic_ziqichen@...cinc.com,
        bmasney@...hat.com, krzysztof.kozlowski@...aro.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 09/15] PM / devfreq: Switch to
 dev_pm_opp_find_freq_{ceil/floor}_indexed() APIs

On Mon, Jul 24, 2023 at 05:06:04AM +0900, Chanwoo Choi wrote:
> Hi,
> 
> On 23. 7. 20. 14:40, Manivannan Sadhasivam wrote:
> > Some devfreq consumers like UFS driver need to work with multiple clocks
> > through the OPP framework. For this reason, OPP framework exposes the
> > _indexed() APIs for finding the floor/ceil of the supplied frequency of
> > the indexed clock. So let's use them in the devfreq driver.
> > 
> > Currently, the clock index of 0 is used which works fine for multiple as
> > well as single clock.
> > 
> > Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>
> > ---
> >  drivers/devfreq/devfreq.c | 14 +++++++-------
> >  1 file changed, 7 insertions(+), 7 deletions(-)
> > 
> > diff --git a/drivers/devfreq/devfreq.c b/drivers/devfreq/devfreq.c
> > index e36cbb920ec8..7686993d639f 100644
> > --- a/drivers/devfreq/devfreq.c
> > +++ b/drivers/devfreq/devfreq.c
> > @@ -88,7 +88,7 @@ static unsigned long find_available_min_freq(struct devfreq *devfreq)
> >  	struct dev_pm_opp *opp;
> >  	unsigned long min_freq = 0;
> >  
> > -	opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &min_freq);
> > +	opp = dev_pm_opp_find_freq_ceil_indexed(devfreq->dev.parent, &min_freq, 0);
> 
> This patch changed the used function from dev_pm_opp_find_freq_ceil
> to dev_pm_opp_find_freq_ceil_indexed even if there are no supporting of the multiple clocks
> and then dev_pm_opp_find_freq_ceil is not removed from OPP.
> 
> I think that it is better to use dev_pm_opp_find_freq_ceil_indexed
> when need to support multiple clocks with real case.
> 

There is the user for dev_pm_opp_find_freq_ceil_indexed() which is the UFS
driver and since UFS is using devfreq, we need this change. I've added this info
in the commit message as well. What am I missing?

- Mani

> >  	if (IS_ERR(opp))
> >  		min_freq = 0;
> >  	else
> > @@ -102,7 +102,7 @@ static unsigned long find_available_max_freq(struct devfreq *devfreq)
> >  	struct dev_pm_opp *opp;
> >  	unsigned long max_freq = ULONG_MAX;
> >  
> > -	opp = dev_pm_opp_find_freq_floor(devfreq->dev.parent, &max_freq);
> > +	opp = dev_pm_opp_find_freq_floor_indexed(devfreq->dev.parent, &max_freq, 0);
> >  	if (IS_ERR(opp))
> >  		max_freq = 0;
> >  	else
> > @@ -196,7 +196,7 @@ static int set_freq_table(struct devfreq *devfreq)
> >  		return -ENOMEM;
> >  
> >  	for (i = 0, freq = 0; i < devfreq->max_state; i++, freq++) {
> > -		opp = dev_pm_opp_find_freq_ceil(devfreq->dev.parent, &freq);
> > +		opp = dev_pm_opp_find_freq_ceil_indexed(devfreq->dev.parent, &freq, 0);
> >  		if (IS_ERR(opp)) {
> >  			devm_kfree(devfreq->dev.parent, devfreq->freq_table);
> >  			return PTR_ERR(opp);
> > @@ -2034,18 +2034,18 @@ struct dev_pm_opp *devfreq_recommended_opp(struct device *dev,
> >  
> >  	if (flags & DEVFREQ_FLAG_LEAST_UPPER_BOUND) {
> >  		/* The freq is an upper bound. opp should be lower */
> > -		opp = dev_pm_opp_find_freq_floor(dev, freq);
> > +		opp = dev_pm_opp_find_freq_floor_indexed(dev, freq, 0);
> >  
> >  		/* If not available, use the closest opp */
> >  		if (opp == ERR_PTR(-ERANGE))
> > -			opp = dev_pm_opp_find_freq_ceil(dev, freq);
> > +			opp = dev_pm_opp_find_freq_ceil_indexed(dev, freq, 0);
> >  	} else {
> >  		/* The freq is an lower bound. opp should be higher */
> > -		opp = dev_pm_opp_find_freq_ceil(dev, freq);
> > +		opp = dev_pm_opp_find_freq_ceil_indexed(dev, freq, 0);
> >  
> >  		/* If not available, use the closest opp */
> >  		if (opp == ERR_PTR(-ERANGE))
> > -			opp = dev_pm_opp_find_freq_floor(dev, freq);
> > +			opp = dev_pm_opp_find_freq_floor_indexed(dev, freq, 0);
> >  	}
> >  
> >  	return opp;
> 
> -- 
> Best Regards,
> Samsung Electronics
> Chanwoo Choi
> 

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