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SubjectRe: [PATCH 1/7] PM / OPP: Introduce a power estimation helper
Hi Viresh,

On Tuesday 29 Jan 2019 at 10:40:30 (+0530), Viresh Kumar wrote:
> > +int of_dev_pm_opp_get_cpu_power(unsigned long *mW, unsigned long *KHz, int cpu)
>
> I would suggest to change the return type to unsigned long and return 0 for
> errors and positive values for mW.

Well, I can't really do that -- this must match the API of PM_EM:

https://elixir.bootlin.com/linux/v5.0-rc4/source/include/linux/energy_model.h#L62

I'll make sure to make that explicit in the commit message for v2.

>
> > +{
> > + unsigned long mV, Hz, MHz;
>
> MHz is used only once, I think you can get rid of it just open code the division
> by 1000000. Maybe remove Hz as well and directly use kHz.

I would expect/hope the compiler will optimize things like that for me
but yes, I can try to reduce a bit the temp variables if you prefer.

>
> > + struct device *cpu_dev;
> > + struct dev_pm_opp *opp;
> > + struct device_node *np;
> > + u32 cap;
> > + u64 tmp;
>
> Name this mW with the above changes.

So that doesn't really work given what I mentioned above.

> > + int ret;
> > +
> > + cpu_dev = get_cpu_device(cpu);
> > + if (!cpu_dev)
> > + return -ENODEV;
> > +
> > + np = of_node_get(cpu_dev->of_node);
> > + if (!np)
> > + return -EINVAL;
> > +
> > + ret = of_property_read_u32(np, "dynamic-power-coefficient", &cap);
> > + of_node_put(np);
> > + if (ret)
> > + return -EINVAL;
> > +
> > + Hz = *KHz * 1000;
> > + opp = dev_pm_opp_find_freq_ceil(cpu_dev, &Hz);
> > + if (IS_ERR(opp))
> > + return -EINVAL;
> > +
> > + mV = dev_pm_opp_get_voltage(opp) / 1000;
> > + dev_pm_opp_put(opp);
> > + if (!mV)
> > + return -EINVAL;
> > +
> > + MHz = Hz / 1000000;
> > + tmp = (u64)cap * mV * mV * MHz;
> > + do_div(tmp, 1000000000);
> > +
> > + *mW = (unsigned long)tmp;
> > + *KHz = Hz / 1000;
> > +
> > + return 0;
> > +}
> > +EXPORT_SYMBOL_GPL(of_dev_pm_opp_get_cpu_power);
> > diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
> > index 0a2a88e5a383..fedde14f5187 100644
> > --- a/include/linux/pm_opp.h
> > +++ b/include/linux/pm_opp.h
> > @@ -322,6 +322,7 @@ int dev_pm_opp_of_get_sharing_cpus(struct device *cpu_dev, struct cpumask *cpuma
> > struct device_node *dev_pm_opp_of_get_opp_desc_node(struct device *dev);
> > struct device_node *dev_pm_opp_get_of_node(struct dev_pm_opp *opp);
> > int of_get_required_opp_performance_state(struct device_node *np, int index);
> > +int of_dev_pm_opp_get_cpu_power(unsigned long *mW, unsigned long *KHz, int cpu);
> > #else
> > static inline int dev_pm_opp_of_add_table(struct device *dev)
> > {
> > @@ -364,6 +365,10 @@ static inline int of_get_required_opp_performance_state(struct device_node *np,
> > {
> > return -ENOTSUPP;
> > }
>
> Add a blank line here. We missed adding the same before
> of_get_required_opp_performance_state() earlier, maybe add the new routine
> before of_get_required_opp_performance_state() and add blank line before and
> after it :)

Sounds good !

>
> > +static inline int of_dev_pm_opp_get_cpu_power(unsigned long *mW, unsigned long *KHz, int cpu)
> > +{
> > + return -ENOTSUPP;
> > +}
> > #endif
> >
> > #endif /* __LINUX_OPP_H__ */
> > --
> > 2.20.1
>
> --
> viresh

Thanks,
Quentin

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