linux-kernel - Re: [PATCHv2 1/1] thermal: cpu_cooling: check for the readiness of cpufreq layer

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Date:	Fri, 28 Nov 2014 11:18:24 +0100
From:	Lukasz Majewski <l.majewski@...ess.pl>
To:	Viresh Kumar <viresh.kumar@...aro.org>,
	Eduardo Valentin <edubezval@...il.com>
Cc:	Linux PM <linux-pm@...r.kernel.org>,
	Lukasz Majewski <l.majewski@...sung.com>,
	LKML <linux-kernel@...r.kernel.org>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	Grant Likely <grant.likely@...aro.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	Zhang Rui <rui.zhang@...el.com>,
	Rob Herring <robh+dt@...nel.org>
Subject: Re: [PATCHv2 1/1] thermal: cpu_cooling: check for the readiness of
 cpufreq layer

On Fri, 28 Nov 2014 13:35:49 +0530
Viresh Kumar <viresh.kumar@...aro.org> wrote:

> On 27 November 2014 at 19:42, Eduardo Valentin <edubezval@...il.com>
> wrote:
> > (I'm sorry VireshK, I am still using my normal practice) :-)
> 
> That's fine :)
> 
> > diff --git a/drivers/thermal/cpu_cooling.c
> > b/drivers/thermal/cpu_cooling.c index 1ab0018..bed3fa2 100644
> > --- a/drivers/thermal/cpu_cooling.c
> > +++ b/drivers/thermal/cpu_cooling.c
> > @@ -440,6 +440,11 @@ __cpufreq_cooling_register(struct device_node
> > *np, int ret = 0, i;
> >         struct cpufreq_policy policy;
> >
> > +       if (!cpufreq_frequency_get_table(0)) {
> > +               pr_err("cpu_cooling: cpufreq layer not ready!
> > Deferring.\n");
> 
> Throwing an error here doesn't look to be the right thing. Ultimately
> we will register the cooling dev when probed again after some time.
> 
> So, a pr_debug() suits more here.
> 
> Also, this breaks existing exynos thermal drivers as they don't handle
> -EPROBE_DEFER well right now.

Unfortunately Viresh is correct here. Current (before rework) Exynos
TMU driver expects that cpu_cooling device will succeed.

> 
> I reached here, because one of my patches had something similar to
> what you wrote. Just for this file though, haven't updated any other
> drivers though.
> 
> Will be sending you my small patchset by end of day today, please see
> if they make any sense at all..

Best regards,
Łukasz Majewski

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