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

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Date:   Wed, 17 Jun 2020 22:13:21 +0530
From:   Sibi Sankar <sibis@...eaurora.org>
To:     Matthias Kaehlcke <mka@...omium.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

On 2020-06-17 03:41, Matthias Kaehlcke wrote:
> 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).

I did consider the case where adjust
voltage fails and we do report the
freq for which it fails for as well.
If adding a OPP fails we will still
it being listed in the sysfs cpufreq
scaling_available_frequencies since
it lists the freq_table in khz there
instead.

-- 
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