linux-kernel - Re: [PATCH v3 3/4] OPP: Add support of "opp-microwatt" for advanced EM registration

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Date:   Thu, 24 Feb 2022 15:12:16 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Lukasz Luba <lukasz.luba@....com>
Cc:     linux-kernel@...r.kernel.org, dietmar.eggemann@....com,
        rafael@...nel.org, daniel.lezcano@...aro.org, nm@...com,
        sboyd@...nel.org, mka@...omium.org, dianders@...omium.org,
        robh+dt@...nel.org, devicetree@...r.kernel.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH v3 3/4] OPP: Add support of "opp-microwatt" for advanced
 EM registration

On 24-02-22, 09:33, Lukasz Luba wrote:
> On 2/24/22 09:13, Viresh Kumar wrote:
> > On 24-02-22, 08:11, Lukasz Luba wrote:
> > > diff --git a/drivers/opp/of.c b/drivers/opp/of.c

> > > +static bool _of_has_opp_microwatt_property(struct device *dev)
> > > +{
> > > +	unsigned long power, freq = 0;
> > > +	struct dev_pm_opp *opp;
> > > +
> > > +	/* Check if at least one OPP has needed property */
> > > +	opp = dev_pm_opp_find_freq_ceil(dev, &freq);
> > > +	if (IS_ERR(opp))
> > > +		return false;
> > > +
> > > +	power = dev_pm_opp_get_power(opp);
> > > +	dev_pm_opp_put(opp);
> > > +	if (!power)
> > 
> > Instead of this heavy stuff, just pick the first OPP from the opp
> > table and see its power-value.
> 
> It is the first opp: freq=0.
> You mean by parsing the the DT node instead, like I had in v2 version?

No, I was thinking if you can simply do:

opp = list_first_entry(&opp_table->opp_list, struct dev_pm_opp, node);

But that requires locking, etc as well. So maybe this is fine.
 
-- 
viresh