linux-kernel - Re: [PATCH v6 4/5] cpufreq: qcom: Update the bandwidth levels on frequency change

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Date:   Tue, 16 Jun 2020 15:11:57 -0700
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Sibi Sankar <sibis@...eaurora.org>
Cc:     viresh.kumar@...aro.org, sboyd@...nel.org,
        georgi.djakov@...aro.org, saravanak@...gle.com, nm@...com,
        bjorn.andersson@...aro.org, agross@...nel.org, rjw@...ysocki.net,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-pm@...r.kernel.org, dianders@...omium.org,
        vincent.guittot@...aro.org, amit.kucheria@...aro.org,
        lukasz.luba@....com, sudeep.holla@....com, smasetty@...eaurora.org,
        linux-arm-msm-owner@...r.kernel.org
Subject: Re: [PATCH v6 4/5] cpufreq: qcom: Update the bandwidth levels on
 frequency change

Hi Sibi,

after doing the review I noticed that Viresh replied on the cover letter
that he picked the series up for v5.9, so I'm not sure if it makes sense
to send a v7.

On Wed, Jun 17, 2020 at 02:35:00AM +0530, Sibi Sankar wrote:

> > > @@ -112,7 +178,7 @@ static int qcom_cpufreq_hw_read_lut(struct
> > > device *cpu_dev,
> > > 
> > >  		if (freq != prev_freq && core_count != LUT_TURBO_IND) {
> > >  			table[i].frequency = freq;
> > > -			dev_pm_opp_add(cpu_dev, freq * 1000, volt);
> > > +			qcom_cpufreq_update_opp(cpu_dev, freq, volt);
> > 
> > This is the cross-validation mentioned above, right? Shouldn't it
> > include
> > a check of the return value?
> 
> Yes, this is the cross-validation step,
> we adjust the voltage if opp-tables are
> present/added successfully and enable
> them, else we would just do a add opp.
> We don't want to exit early on a single
> opp failure. We will error out a bit
> later if the opp-count ends up to be
> zero.

At least an error/warning message would seem convenient when adjusting/adding
an OPP fails, otherwise you would only notice by looking at the sysfs
attributes (if you'd even spot a single/few OPPs to be missing).