linux-kernel - Re: [PATCH v3 5/5] thermal: cpu_cooling: update the cpu device when cpufreq updates the policy cpu

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Date:	Tue, 03 Mar 2015 15:34:55 +0000
From:	Kapileshwar Singh <kapileshwar.singh@....com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
CC:	Javi Merino <Javi.Merino@....com>,
	Eduardo Valentin <edubezval@...il.com>,
	Zhang Rui <rui.zhang@...el.com>,
	Linux PM list <linux-pm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Punit Agrawal <Punit.Agrawal@....com>,
	Lina Iyer <lina.iyer@...aro.org>,
	Mark Brown <broonie@...nel.org>, Jon Medhurst <tixy@...aro.org>
Subject: Re: [PATCH v3 5/5] thermal: cpu_cooling: update the cpu device when
 cpufreq updates the policy cpu



On 03/03/15 15:29, Viresh Kumar wrote:
> On 3 March 2015 at 20:39, Kapileshwar Singh <kapileshwar.singh@....com> wrote:
> 
>> I did test this but we were working with the assumption that OPPs should be populated for all the CPUs and also that OPPs are lost for a hotplugged CPU which I see is not the case.
> 
> Then what did you test? My point here is, even with the latest patches
> that you have
> sent, you wouldn't be able to get the OPPs once policy->cpu goes down. So, how
> did this worked for you ?

We were basing our fix on possibility of having OPPs for all the CPUs and we incorrectly attributed the erroneous OPP we got from dev_pm_opp_find_freq_exact to the missing OPPs in the other CPUs.

> 
>> We have looked at this more closely and found that problem lies in:
>>
>>         freq = cpufreq_quick_get(cpumask_any(&cpufreq_device->allowed_cpus));
>>
>> which returns a NULL frequency as we are not checking for online CPUs here. We shall come up with a fix for this. Many thanks for helping us with the investigation.
> 
> Right.
> 

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