Re: [PATCH v6 1/2] PM / Domains: Add support for 'required-opps' to set default perf state
From: Dmitry Osipenko
Date: Mon Aug 09 2021 - 20:38:05 EST
10.08.2021 02:46, Dmitry Osipenko пишет:
> 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;
> }
>
Although, thinking a bit more about this, it should be better to skip
setting perf state in a case of power_on=false and let drivers to handle
it, IMO. Too much trouble with it for the core.