linux-kernel - Re: [PATCH V2 01/16] PM / OPP: get/put regulators from OPP core

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Date:	Mon, 8 Feb 2016 14:52:05 -0800
From:	Stephen Boyd <sboyd@...eaurora.org>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Rafael Wysocki <rjw@...ysocki.net>, linaro-kernel@...ts.linaro.org,
	linux-pm@...r.kernel.org, nm@...com,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Len Brown <len.brown@...el.com>,
	open list <linux-kernel@...r.kernel.org>,
	Pavel Machek <pavel@....cz>, Viresh Kumar <vireshk@...nel.org>
Subject: Re: [PATCH V2 01/16] PM / OPP: get/put regulators from OPP core

On 02/02, Viresh Kumar wrote:
> On 01-02-16, 18:29, Stephen Boyd wrote:
> > I'm still lost why we need this API. When the OPP is torn down we
> > can call regulator_put there instead. The same style seems to be
> > done for supported hw, and prop_name, which doesn't make any
> > sense either. Just tear everything down when there aren't any
> > more OPPs in the table.
> 
> I explained that earlier as well, but you never replied to that :)
> Let me paste that again here:
> 
> Consider this case:
> - Platform code sets regulator for cpuX (Create OPP-table struct and
>   set regulator)
> - insmod cpufreq-dt.ko (Fill OPP table)
> - rmmod cpufreq-dt.ko (Remove OPP table and struct, according to your
>   suggestion)
> - insmod cpufreq-dt.ko (No regulator found).
> 
> The platform code is supposed to set regulator, supported-hw,
> prop-name only once from some init-code. And it should just work out
> of the box after that. And so these calls are really required.
> 

Ok the sequence makes sense now that it's clearly explained. I
wonder if we should create and destroy OPP tables when a device
is created and destroyed instead of triggering that from a
driver. I suppose not creating the tables until they're used is
good for saving memory though?

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