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Date: Tue, 10 Aug 2021 14:57:05 +0530 From: Viresh Kumar <viresh.kumar@...aro.org> To: Lukasz Luba <lukasz.luba@....com> Cc: Andy Gross <agross@...nel.org>, Rafael Wysocki <rjw@...ysocki.net>, Vincent Donnefort <vincent.donnefort@....com>, 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 10-08-21, 10:17, Lukasz Luba wrote: > Hi Viresh, > > I like the idea, only small comments here in the cover letter. > > On 8/10/21 8:36 AM, Viresh Kumar wrote: > > Provide a cpufreq driver flag so drivers can ask the cpufreq core to register > > with the EM core on their behalf. This allows us to get rid of duplicated code > > in the drivers and fix the unregistration part as well, which none of the > > drivers have done until now. > > The EM is never freed for CPUs by design. The unregister function was > introduced for devfreq devices. I see. So if a cpufreq driver unregisters and registers again, it will be required to use the entries created by the registration itself, right ? Technically speaking, it is better to unregister and free any related resources and parse everything again. Lets say, just for fun, I want to test two copies of a cpufreq driver (providing different set of freq-tables). I build both of them as modules, insert the first version, remove it, insert the second one. Ideally, this should just work as expected. But I don't think it will in this case as you never parse the EM stuff again. Again, since the routine is there already, I think it is better/fine to just use it. > > This would also make the registration with EM core to happen only after policy > > is fully initialized, and the EM core can do other stuff from in there, like > > marking frequencies as inefficient (WIP). Though this patchset is useful without > > that work being done and should be merged nevertheless. > > > > This doesn't update scmi cpufreq driver for now as it is a special case and need > > to be handled differently. Though we can make it work with this if required. > > The scmi cpufreq driver uses direct EM API, which provides flexibility > and should stay as is. Right, so I left it as is for now. -- viresh
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