linux-kernel - Re: [PATCH v5 23/23] Documentation: EM: Update with runtime modification design

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Date: Wed, 20 Dec 2023 10:08:20 +0800
From: Xuewen Yan <xuewen.yan94@...il.com>
To: Lukasz Luba <lukasz.luba@....com>
Cc: linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org, rafael@...nel.org, 
	dietmar.eggemann@....com, rui.zhang@...el.com, amit.kucheria@...durent.com, 
	amit.kachhap@...il.com, daniel.lezcano@...aro.org, viresh.kumar@...aro.org, 
	len.brown@...el.com, pavel@....cz, mhiramat@...nel.org, qyousef@...alina.io, 
	wvw@...gle.com
Subject: Re: [PATCH v5 23/23] Documentation: EM: Update with runtime
 modification design

On Tue, Dec 19, 2023 at 5:31 PM Lukasz Luba <lukasz.luba@....com> wrote:
>
>
>
> On 12/19/23 06:22, Xuewen Yan wrote:
> > Hi Lukasz,
> >
> > On Wed, Nov 29, 2023 at 7:11 PM Lukasz Luba <lukasz.luba@....com> wrote:
>
> [snip]
>
> >> +
> >> +  -> drivers/soc/example/example_em_mod.c
> >> +
> >> +  01   static void foo_get_new_em(struct device *dev)
> >
> > Because now some drivers use the dev_pm_opp_of_register_em() to
> > register energy model,
> > and maybe we can add a new function to update the energy model using
> > "EM_SET_ACTIVE_POWER_CB(em_cb, cb)"
> > instead of letting users set power again?
> >
>
> There are different usage of this EM feature:
> 1. Adjust power values after boot is finish and e.g. ASV in Exynos
>     has adjusted new voltage values in the OPP framework. It's
>     due to chip binning. I have described that in conversation
>     below patch 22/23. I'm going to send a patch for that
>     platform and OPP fwk later as a follow up to this series.

I understand what you mean, what I mean is that if we can provide an
interface for changing EM of opp fwk, it will be more friendly for
those users who use opp, because then they don't have to calculate the
new EM by themselves, but only need After updating the voltage of opp,
just call this interface directly.

BR
---
xuewen

> 2. Change the EM power values after long gaming, when the GPU
>     heats up the SoC heavily and CPUs start increase the leakage
> 3. Change the EM for long running heavy apps, e.g. video conference app,
>     which is using camera w/ image AI and filters (so some heavy stuff)
> 4. any other optimization that vendor/OEM like to have for