linux-kernel - Re: [PATCH v6 1/2] PM / Domains: Add support for 'required-opps' to set default perf state

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Message-ID: <9588f01d-1cb6-7ca3-eb41-74259f1678f6@gmail.com>
Date:   Tue, 10 Aug 2021 02:46:43 +0300
From:   Dmitry Osipenko <digetx@...il.com>
To:     Rajendra Nayak <rnayak@...eaurora.org>, ulf.hansson@...aro.org,
        bjorn.andersson@...aro.org, viresh.kumar@...aro.org
Cc:     linux-pm@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org,
        swboyd@...omium.org, rojay@...eaurora.org, stephan@...hold.net
Subject: Re: [PATCH v6 1/2] PM / Domains: Add support for 'required-opps' to
 set default perf state

10.08.2021 01:44, Dmitry Osipenko пишет:
> 10.08.2021 01:26, Dmitry Osipenko пишет:
>> 04.08.2021 13:58, Rajendra Nayak пишет:
>>> @@ -2637,6 +2643,8 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>>>  {
>>>  	struct of_phandle_args pd_args;
>>>  	struct generic_pm_domain *pd;
>>> +	struct device_node *np;
>>> +	int pstate;
>>>  	int ret;
>>>  
>>>  	ret = of_parse_phandle_with_args(dev->of_node, "power-domains",
>>> @@ -2675,10 +2683,26 @@ static int __genpd_dev_pm_attach(struct device *dev, struct device *base_dev,
>>>  		genpd_unlock(pd);
>>>  	}
>>>  
>>> -	if (ret)
>>> +	if (ret) {
>>>  		genpd_remove_device(pd, dev);
>>> +		return -EPROBE_DEFER;
>>> +	}
>>> +
>>> +	/* Set the default performance state */
>>> +	np = dev->of_node;
>>> +	if (of_parse_phandle(np, "required-opps", index)) {

The OF node returned by of_parse_phandle() must be put.

>>> +		pstate = of_get_required_opp_performance_state(np, index);

If you have more than one power domain, then this will override the
pstate which was set for a previous domain. This code doesn't feel solid
to me, at least a clarifying comment is needed about how it's supposed
to work.

>>> +		if (pstate < 0) {
>>> +			ret = pstate;
>>> +			dev_err(dev, "failed to set required performance state for power-domain %s: %d\n",
>>> +				pd->name, ret);
>>> +		} else {
>>> +			dev_pm_genpd_set_performance_state(dev, pstate);
> 
> Where is error handling?
> 
>>> +			dev_gpd_data(dev)->default_pstate = pstate;
>>> +		}
>>> +	}
>>
>> Why performance state is set after genpd_power_on()?

Should set_performance_state() be invoked when power_on=false?

I assume it should be:

if (power_on) {
	dev_pm_genpd_set_performance_state(dev, pstate);
	dev_gpd_data(dev)->default_pstate = pstate;
} else {
	dev_gpd_data(dev)->rpm_pstate = pstate;
}