linux-kernel - Re: [PATCH] cpufreq: powernv: Register the driver with reboot notifier

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Message-ID: <CAKohpon8ANWoy52B=_nSuNyHALrsQOLX4cA+690E=CifnVRFtg@mail.gmail.com>
Date:	Thu, 21 Aug 2014 11:56:52 +0530
From:	Viresh Kumar <viresh.kumar@...aro.org>
To:	Shilpasri G Bhat <shilpabhatppc@...il.com>
Cc:	Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] cpufreq: powernv: Register the driver with reboot notifier

On 21 August 2014 10:36, Shilpasri G Bhat <shilpabhatppc@...il.com> wrote:
> The intention here is stop the cpufreq governor and then to set the cpus to
> nominal frequency so as to ensure that the frequency won't be changed later.
>
> The .suspend callback of the driver is not called during reboot/kexec.
> So we need an explicit reboot notifier to call cpufreq-suspend() to
> suffice the requirement.

Hi Shilpa,

No, we can't allow any platform driver to misuse cpufreq_suspend().
Platform drivers aren't *allowed* to call this routine.

Now the deal is how do we move to nominal frequency on reboot..
@Rafael: Any suggestions? How do we ensure that governors
are stopped on these notifiers, or if there is some other solution here?
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