linux-kernel - Re: [PATCH V2 2/6] Thermal: make sure cpufreq cooling register after cpufreq driver

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Date:	Tue, 30 Oct 2012 09:59:23 +0100
From:	Hongbo Zhang <hongbo.zhang@...aro.org>
To:	Amit Kachhap <amit.kachhap@...aro.org>
Cc:	linaro-dev@...ts.linaro.org, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, STEricsson_nomadik_linux@...t.st.com,
	kernel@...oocommunity.org, linaro-kernel@...ts.linaro.org,
	"hongbo.zhang" <hongbo.zhang@...aro.com>, patches@...aro.org
Subject: Re: [PATCH V2 2/6] Thermal: make sure cpufreq cooling register after
 cpufreq driver

On 29 October 2012 12:42, Amit Kachhap <amit.kachhap@...aro.org> wrote:
> On 24 October 2012 17:28, hongbo.zhang <hongbo.zhang@...aro.org> wrote:
>> From: "hongbo.zhang" <hongbo.zhang@...aro.com>
>>
>> The cpufreq works as a cooling device, so the cooling layer should check if the
>> cpufreq driver is initialized or not.
>>
>> Signed-off-by: hongbo.zhang <hongbo.zhang@...aro.com>
>> ---
>>  drivers/thermal/cpu_cooling.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
>> index b6b4c2a..7519a0b 100644
>> --- a/drivers/thermal/cpu_cooling.c
>> +++ b/drivers/thermal/cpu_cooling.c
>> @@ -354,6 +354,10 @@ struct thermal_cooling_device *cpufreq_cooling_register(
>>         int ret = 0, i;
>>         struct cpufreq_policy policy;
>>
>> +       /* make sure cpufreq driver has been initialized */
>> +       if (!cpufreq_frequency_get_table(cpumask_any(clip_cpus)))
>> +               return ERR_PTR(-EPROBE_DEFER);
>> +
> Hi Hongbo,
>
> I am not against this change but this might cause unnecessary delay in
> probe thread. I also thought about it but have not put this
> restriction. Actually you can put a check in platform_bind for this
> condition and defer the binding till the time actual throttling
> starts. So basically only after throttling cpufreq_table is needed.
> (See my implementation exynos_thermal.c).
In fact, this piece of checking code was in my
db8500_cpufreq_cooling_probe() before, I will move it back there
again, and the ST-E's policy is separating cooling devs and thermal
zone, so cannot be in binding function on my platform, only in probe
function instead.
>
> Thanks,
> Amit Daniel
>>         list_for_each_entry(cpufreq_dev, &cooling_cpufreq_list, node)
>>                 cpufreq_dev_count++;
>>
>> --
>> 1.7.11.3
>>
>>
>> _______________________________________________
>> linaro-dev mailing list
>> linaro-dev@...ts.linaro.org
>> http://lists.linaro.org/mailman/listinfo/linaro-dev
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