linux-kernel - Re: [PATCH 1/4] opp: add dev_pm_opp_is

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Message-ID: <20150729105347.GA23865@amd>
Date:	Wed, 29 Jul 2015 12:53:47 +0200
From:	Pavel Machek <pavel@....cz>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	Rafael Wysocki <rjw@...ysocki.net>, linaro-kernel@...ts.linaro.org,
	linux-pm@...r.kernel.org, b.zolnierkie@...sung.com, nm@...com,
	sboyd@...eaurora.org, Tomasz Figa <tomasz.figa@...il.com>,
	Michael Turquette <mturquette@...libre.com>,
	Javier Martinez Canillas <javier@...hile0.org>,
	Thomas Abraham <thomas.ab@...sung.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Len Brown <len.brown@...el.com>,
	open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/4] opp: add dev_pm_opp_is_turbo() helper

On Wed 2015-07-29 15:54:35, Viresh Kumar wrote:
> On 28-07-15, 16:27, Pavel Machek wrote:
> > Typo.
> > 
> > And this is not exactly most helpful comment. opp is turbo... returns
> > if opp was turbo. Explanation what "turbo" means in this context would
> > be nice. I'm pretty sure it is not about air compression :-).
> 
> Does this make it any better:

Yes.

So any combination of normal OPPs can be sustained for arbitrary time
within the temperature range?

And as soon as any turbo OPP is enabled, we produce more heat than
TDP?

Thanks,
								Pavel


> diff --git a/drivers/base/power/opp.c b/drivers/base/power/opp.c
> index e039cf024a6c..da8ec7f824d5 100644
> --- a/drivers/base/power/opp.c
> +++ b/drivers/base/power/opp.c
> @@ -281,9 +281,13 @@ unsigned long dev_pm_opp_get_freq(struct dev_pm_opp *opp)
>  EXPORT_SYMBOL_GPL(dev_pm_opp_get_freq);
>  
>  /**
> - * dev_pm_opp_is_turbo() - Returns true if opp was trubo OPP
> + * dev_pm_opp_is_turbo() - Returns if opp is turbo OPP or not
>   * @opp: opp for which turbo mode is being verified
>   *
> + * Turbo OPPs are not for normal use, and can be enabled (under certain
> + * conditions) for short duration of times to finish high throughput work
> + * quickly. Running on them for longer times may overheat the chip.
> + *
>   * Return: true if opp is turbo opp, else false.
>   *
>   * Locking: This function must be called under rcu_read_lock(). opp is a rcu
> 
> 

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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