linux-kernel - Re: [PATCH 1/2] OPP: Add API to update EM after adjustment of voltage for OPPs

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Date: Tue, 26 Dec 2023 10:42:28 +0530
From: Viresh Kumar <viresh.kumar@...aro.org>
To: Lukasz Luba <lukasz.luba@....com>
Cc: linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
	dietmar.eggemann@....com, linux-arm-kernel@...ts.infradead.org,
	sboyd@...nel.org, nm@...com, linux-samsung-soc@...r.kernel.org,
	daniel.lezcano@...aro.org, rafael@...nel.org,
	krzysztof.kozlowski@...aro.org, alim.akhtar@...sung.com,
	m.szyprowski@...sung.com, xuewen.yan94@...il.com,
	mhiramat@...nel.org, qyousef@...alina.io, wvw@...gle.com
Subject: Re: [PATCH 1/2] OPP: Add API to update EM after adjustment of
 voltage for OPPs

On 20-12-23, 11:03, Lukasz Luba wrote:
> There are device drivers which can modify voltage values for OPPs. It
> could be due to the chip binning and those drivers have specific chip
> knowledge about this. This adjustment can happen after Energy Model is
> registered, thus EM can have stale data about power.
> 
> Introduce new API function which can be used by device driver which
> adjusted the voltage for OPPs. The implementation takes care about
> calculating needed internal details in the new EM table ('cost' field).
> It plugs in the new EM table to the framework so other subsystems would
> use the correct data.
> 
> Signed-off-by: Lukasz Luba <lukasz.luba@....com>
> ---
>  drivers/opp/of.c       | 69 ++++++++++++++++++++++++++++++++++++++++++
>  include/linux/pm_opp.h |  6 ++++
>  2 files changed, 75 insertions(+)
> 
> diff --git a/drivers/opp/of.c b/drivers/opp/of.c
> index 81fa27599d58..992434c0b711 100644
> --- a/drivers/opp/of.c
> +++ b/drivers/opp/of.c
> @@ -1596,3 +1596,72 @@ int dev_pm_opp_of_register_em(struct device *dev, struct cpumask *cpus)
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(dev_pm_opp_of_register_em);
> +
> +/**
> + * dev_pm_opp_of_update_em() - Update Energy Model with new power values
> + * @dev		: Device for which an Energy Model has to be registered
> + *
> + * This uses the "dynamic-power-coefficient" devicetree property to calculate
> + * power values for EM. It uses the new adjusted voltage values known for OPPs
> + * which have changed after boot.
> + */
> +int dev_pm_opp_of_update_em(struct device *dev)

I don't see anything OPP or OF related in this function, I don't think it needs
to be part of the OPP core. You just want to reuse _get_power() I guess, which
can be exported then.

This should really be part of the EM core instead.

-- 
viresh