linux-kernel - Re: [[PATCH v2 2/2] OPP: Add 'opp-microwatt' parsing for advanced EM registration

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Date:   Wed, 23 Feb 2022 08:59:48 +0000
From:   Lukasz Luba <lukasz.luba@....com>
To:     Viresh Kumar <viresh.kumar@...aro.org>
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 v2 2/2] OPP: Add 'opp-microwatt' parsing for advanced EM
 registration



On 2/23/22 05:53, Viresh Kumar wrote:
> On 22-02-22, 14:07, Lukasz Luba wrote:
>> +static int _of_find_opp_microwatt_property(struct device *dev)
>> +{
>> +	unsigned long freq = 0;
>> +	struct dev_pm_opp *opp;
>> +	struct device_node *np;
>> +	struct property *prop;
>> +
>> +	/* We only support "operating-points-v2" */
>> +	np = dev_pm_opp_of_get_opp_desc_node(dev);
>> +	if (!np)
>> +		return -EINVAL;
>> +
>> +	of_node_put(np);
>> +
>> +	/* Check if an OPP has needed property */
>> +	opp = dev_pm_opp_find_freq_ceil(dev, &freq);
>> +	if (IS_ERR(opp))
>> +		return -EINVAL;
>> +
>> +	prop = of_find_property(opp->np, "opp-microwatt", NULL);
>> +	dev_pm_opp_put(opp);
>> +	if (!prop)
>> +		return -EINVAL;
>> +
>> +	return 0;
>> +}
> 
> Please follow everything just like opp-microvolt is defined. Create a new field
> in the struct dev_pm_opp, initialize it only once when the OPP is created, that
> field should be used here instead of parsing the DT here again. There also needs
> to be a debug file in debugfs for this new field.
> 
> Search for "supply" and "microvolt" in the OPP core, you will see all the places
> that need it.
> 

OK, so you want to have this available for the whole system. I can do
that. I would go for one value of power and try to fit into the
opp_parse_supplies() code. As far as I can see in the
dev_pm_opp_get_voltage() the simple solution: supplier[0] and u_volt
is used. I would go for similar solution for u_watt.
There is even a single u_amp and no _max, _min variants, so should be
good..