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SubjectRe: [PATCH v2 1/5] PM / OPP: Introduce a power estimation helper
On 30-01-19, 17:05, Quentin Perret wrote:
> +static int __maybe_unused _get_cpu_power(unsigned long *mW, unsigned long *kHz,
> + int cpu)
> +{
> + struct device *cpu_dev;
> + struct dev_pm_opp *opp;
> + struct device_node *np;
> + unsigned long mV, Hz;
> + u32 cap;
> + u64 tmp;
> + 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;

The voltage is also stored as triplet now a days and we must consider
the higher value for these calculations. Also what about the case of
multiple regulators here or performance-states ?

> + dev_pm_opp_put(opp);
> + if (!mV)
> + return -EINVAL;
> +
> + tmp = (u64)cap * mV * mV * (Hz / 1000000);
> + do_div(tmp, 1000000000);
> +
> + *mW = (unsigned long)tmp;

I was thinking will it be better if we just save this information in
opp->power field during init, so we can just read a value here
instead. But I am still not sure :(

> + *kHz = Hz / 1000;
> +
> + return 0;
> +}
> +
> +/**
> + * dev_pm_opp_of_register_em() - Attempt to register an Energy Model
> + * @cpus : CPUs for which an Energy Model has to be registered
> + * @nr_opp : Number of OPPs to register in the Energy Model
> + *
> + * This checks whether the "dynamic-power-coefficient" devicetree binding has
> + * been specified, and tries to register an Energy Model with it if it has.
> + */
> +void dev_pm_opp_of_register_em(struct cpumask *cpus, int nr_opp)
> +{
> + struct em_data_callback em_cb = EM_DATA_CB(_get_cpu_power);
> + int ret, cpu = cpumask_first(cpus);
> + struct device *cpu_dev;
> + struct device_node *np;
> + u32 cap;
> +
> + cpu_dev = get_cpu_device(cpu);
> + if (!cpu_dev)
> + return;
> +
> + np = of_node_get(cpu_dev->of_node);
> + if (!np)
> + return;
> +
> + /* Don't register an EM without the right DT binding */
> + ret = of_property_read_u32(np, "dynamic-power-coefficient", &cap);
> + of_node_put(np);
> + if (ret || !cap)
> + return;

What if no voltage is supplied in DT ?

> +
> + em_register_perf_domain(cpus, nr_opp, &em_cb);
> +}
> +EXPORT_SYMBOL_GPL(dev_pm_opp_of_register_em);
> diff --git a/include/linux/pm_opp.h b/include/linux/pm_opp.h
> index b895f4e79868..58ae08b024bd 100644
> --- a/include/linux/pm_opp.h
> +++ b/include/linux/pm_opp.h
> @@ -327,6 +327,7 @@ 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);
> +void dev_pm_opp_of_register_em(struct cpumask *cpus, int nr_opp);
> #else
> static inline int dev_pm_opp_of_add_table(struct device *dev)
> {
> @@ -365,6 +366,11 @@ static inline struct device_node *dev_pm_opp_get_of_node(struct dev_pm_opp *opp)
> {
> return NULL;
> }
> +
> +static inline void dev_pm_opp_of_register_em(struct cpumask *cpus, int nr_opp)
> +{
> +}
> +
> static inline int of_get_required_opp_performance_state(struct device_node *np, int index)
> {
> return -ENOTSUPP;
> --
> 2.20.1

--
viresh

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