linux-kernel - Re: [PATCH 04/13] cpufreq: qcom: Refactor the driver to make it easier to extend

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Message-ID: <20190716111115.GA13918@centauri>
Date:   Tue, 16 Jul 2019 13:11:15 +0200
From:   Niklas Cassel <niklas.cassel@...aro.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     Andy Gross <agross@...nel.org>, Ilia Lin <ilia.lin@...nel.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        linux-arm-msm@...r.kernel.org, jorge.ramirez-ortiz@...aro.org,
        sboyd@...nel.org, vireshk@...nel.org, bjorn.andersson@...aro.org,
        ulf.hansson@...aro.org, linux-pm@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 04/13] cpufreq: qcom: Refactor the driver to make it
 easier to extend

On Wed, Jul 10, 2019 at 12:00:26PM +0530, Viresh Kumar wrote:
> On 05-07-19, 11:57, Niklas Cassel wrote:
> > +	drv->opp_tables = kcalloc(num_possible_cpus(), sizeof(*drv->opp_tables),
> > +				  GFP_KERNEL);
> > +	if (!drv->opp_tables) {
> > +		ret = -ENOMEM;
> > +		goto free_drv;
> > +	}
> >  
> >  	for_each_possible_cpu(cpu) {
> >  		cpu_dev = get_cpu_device(cpu);
> > @@ -166,19 +195,23 @@ static int qcom_cpufreq_probe(struct platform_device *pdev)
> >  			goto free_opp;
> >  		}
> >  
> > -		opp_tables[cpu] = dev_pm_opp_set_supported_hw(cpu_dev,
> > -							      &versions, 1);
> > -		if (IS_ERR(opp_tables[cpu])) {
> > -			ret = PTR_ERR(opp_tables[cpu]);
> > -			dev_err(cpu_dev, "Failed to set supported hardware\n");
> > -			goto free_opp;
> > +		if (drv->data->get_version) {
> 
> Why depend on get_version here ? The OPP table is already allocated
> unconditionally.

Since the reading of the speedbin efuse is now optional,
it is now inside "if (drv->data->get_version)".

So if I don't also protect "dev_pm_opp_set_supported_hw()"
with "if (drv->data->get_version)" I get:

[    3.135092] cpu cpu0: _opp_is_supported: failed to read opp-supported-hw property at index 0: -22
[    3.139364] cpu cpu0: _opp_is_supported: failed to read opp-supported-hw property at index 0: -22
[    3.148330] cpu cpu0: _opp_is_supported: failed to read opp-supported-hw property at index 0: -22

Probably since drv->versions is initialized to 0,
and if there is no opp-supported-hw in device tree,
OPP framework prints failures.

So it feels safest to only call dev_pm_opp_set_supported_hw()
if we know that we are supposed to parse the speedbin efuse.


Kind regards,
Niklas

> 
> > +			drv->opp_tables[cpu] =
> > +				dev_pm_opp_set_supported_hw(cpu_dev,
> > +							    &drv->versions, 1);
> > +			if (IS_ERR(drv->opp_tables[cpu])) {
> > +				ret = PTR_ERR(drv->opp_tables[cpu]);
> > +				dev_err(cpu_dev,
> > +					"Failed to set supported hardware\n");
> > +				goto free_opp;
> > +			}
> >  		}
> >  	}
> 
> -- 
> viresh