linux-kernel - Re: [PATCH v6 2/8] cpufreq: Add boost frequency support in core

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Date:	Mon, 12 Aug 2013 11:07:41 +0200
From:	Lukasz Majewski <l.majewski@...sung.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	"Rafael J. Wysocki" <rjw@...k.pl>, Zhang Rui <rui.zhang@...el.com>,
	Eduardo Valentin <eduardo.valentin@...com>,
	"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
	Linux PM list <linux-pm@...r.kernel.org>,
	Jonghwa Lee <jonghwa3.lee@...sung.com>,
	Lukasz Majewski <l.majewski@...ess.pl>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	Myungjoo Ham <myungjoo.ham@...sung.com>, durgadoss.r@...el.com,
	Lists linaro-kernel <linaro-kernel@...ts.linaro.org>
Subject: Re: [PATCH v6 2/8] cpufreq: Add boost frequency support in core

On Fri, 26 Jul 2013 15:06:45 +0530 Viresh Kumar viresh.kumar@...aro.org
wrote,
> On 26 July 2013 14:03, Lukasz Majewski <l.majewski@...sung.com> wrote:
> > The problem here is with the cpufreq_driver->set_boost() call.
> >
> > I tried to avoid acquiring lock at one function and release it at
> > another (in this case cpufreq_boost_set_sw), especially since the
> > __cpufreq_governor() acquires its own lock - good place for
> > deadlock.
> >
> > Is it OK for you to grab lock at one function
> > (cpufreq_boost_trigger_state()) and then at other function
> > (cpufreq_boost_set_sw) release it before calling
> > __cpufreq_governor() and grab it again after its completion?
> 
> Problem is not only that.. but we shouldn't call boost_set() of
> drivers like acpi-cpufreq with this lock..... Leave it as it is for
> now.. Let me see if I can think of any problems that can happen due
> to this.

Do you have any second thoughts about this? Shall I leave it as it is
now?

-- 
Best regards,

Lukasz Majewski

Samsung R&D Institute Poland (SRPOL) | Linux Platform Group
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