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

From: Lukasz Majewski <l.majewski@majess.pl>
To: Viresh Kumar <viresh.kumar@linaro.org>,
	Eduardo Valentin <edubezval@gmail.com>
Cc: "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	Lukasz Majewski <l.majewski@samsung.com>,
	Kukjin Kim <kgene.kim@samsung.com>,
	Linux PM <linux-pm@vger.kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Rob Herring <robh+dt@kernel.org>,
	linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
	Grant Likely <grant.likely@linaro.org>,
	Zhang Rui <rui.zhang@intel.com>,
	"linux-arm-kernel@lists.infradead.org"
	<linux-arm-kernel@lists.infradead.org>
Subject: Re: [PATCHv2 1/1] thermal: cpu_cooling: check for the readiness of cpufreq layer
Date: Fri, 28 Nov 2014 11:18:24 +0100	[thread overview]
Message-ID: <20141128111824.533c4641@jawa> (raw)
In-Reply-To: <CAKohponu_PRrqsuMdCJDznhiO_-=iCaYPhCCad8F4WS3rNxo5A@mail.gmail.com>

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

> On 27 November 2014 at 19:42, Eduardo Valentin <edubezval@gmail.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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