linux-kernel - Re: [PATCH 0/8] cpufreq: Auto-register with energy model

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Message-ID: <20210811095311.e6wnma2ubkqdtuic@vireshk-i7>
Date:   Wed, 11 Aug 2021 15:23:11 +0530
From:   Viresh Kumar <viresh.kumar@...aro.org>
To:     Quentin Perret <qperret@...gle.com>
Cc:     Rafael Wysocki <rjw@...ysocki.net>,
        Vincent Donnefort <vincent.donnefort@....com>,
        lukasz.luba@....com, Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Cristian Marussi <cristian.marussi@....com>,
        Fabio Estevam <festevam@...il.com>,
        Kevin Hilman <khilman@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        NXP Linux Team <linux-imx@....com>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Sascha Hauer <s.hauer@...gutronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        Sudeep Holla <sudeep.holla@....com>, linux-pm@...r.kernel.org,
        Vincent Guittot <vincent.guittot@...aro.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-arm-msm@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mediatek@...ts.infradead.org, linux-omap@...r.kernel.org
Subject: Re: [PATCH 0/8] cpufreq: Auto-register with energy model

On 11-08-21, 10:48, Quentin Perret wrote:
> I think this should work, but perhaps will be a bit tricky for cpufreq
> driver developers as they need to have a pretty good understanding of
> the stack to know that they should do the registration from here and not
> ->init() for instance. Suggested alternative: we introduce a ->register_em()
> callback to cpufreq_driver, and turn dev_pm_opp_of_register_em() into a
> valid handler for this callback. This should 'document' things a bit
> better, avoid some of the problems your other series tried to achieve, and
> allow us to call the EM registration in exactly the right place from
> cpufreq core. On the plus side, we could easily make this work for e.g.
> the SCMI driver which would only need to provide its own version of
> ->register_em().
> 
> Thoughts?

I had exactly the same thing in mind, but was thinking of two
callbacks, to register and unregister. But yeah, we aren't going to
register for now at least :)

I wasn't sure if that should be done or not, since we also have
ready() callback. So was reluctant to suggest it earlier. But that can
work well as well.

-- 
viresh