linux-kernel - Re: [PATCH V2 4/7] thermal/drivers/Kconfig: Convert the CPU cooling device to a choice

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Message-ID: <1dd1fe8a-d7e7-b4c7-9114-c9de41fc9284@linaro.org>
Date:   Fri, 23 Feb 2018 10:10:59 +0100
From:   Daniel Lezcano <daniel.lezcano@...aro.org>
To:     Viresh Kumar <viresh.kumar@...aro.org>
Cc:     edubezval@...il.com, kevin.wangtao@...aro.org, leo.yan@...aro.org,
        vincent.guittot@...aro.org, amit.kachhap@...il.com,
        linux-kernel@...r.kernel.org, javi.merino@...nel.org,
        rui.zhang@...el.com, daniel.thompson@...aro.org,
        linux-pm@...r.kernel.org
Subject: Re: [PATCH V2 4/7] thermal/drivers/Kconfig: Convert the CPU cooling
 device to a choice

On 23/02/2018 06:24, Viresh Kumar wrote:
> On 21-02-18, 16:29, Daniel Lezcano wrote:
>> The next changes will add new way to cool down a CPU. In order to
>> sanitize and make the overall cpu cooling code consistent and robust
>> we must prevent the cpu cooling devices to co-exists with the same
>> purpose at the same time in the kernel.
>>
>> Make the CPU cooling device a choice in the Kconfig, so only one CPU
>> cooling strategy can be chosen.
> 
> Daniel T. already raised his concern (which I share too) about the
> multi-platform builds, where we would want this to be runtime
> selectable. I am fine with your approach of making that possible later
> on, but I would really like that to be merged before the combo thing
> comes in. So, I would suggest to merge stuff in this order:
> 
> - this series
> - runtime selectable strategy
> - combo stuff
> 
> I hope that would be fine ?

Yes, for me it is ok. So meanwhile we can also check the cpufreq cooling
device unregistering at suspend/resume/hotplug and hopefully that will
simplify the addition of the combo cooling device.


>> Signed-off-by: Daniel Lezcano <daniel.lezcano@...aro.org>
>> ---
>>  drivers/thermal/Kconfig       | 20 +++++++++++++++++---
>>  drivers/thermal/cpu_cooling.c |  2 ++
>>  include/linux/cpu_cooling.h   |  6 +++---
>>  3 files changed, 22 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/thermal/Kconfig b/drivers/thermal/Kconfig
>> index b6adc54..5aaae1b 100644
>> --- a/drivers/thermal/Kconfig
>> +++ b/drivers/thermal/Kconfig
>> @@ -142,17 +142,31 @@ config THERMAL_GOV_POWER_ALLOCATOR
>>  	  allocating and limiting power to devices.
>>  
>>  config CPU_THERMAL
>> -	bool "generic cpu cooling support"
>> -	depends on CPU_FREQ
>> +	bool "Generic cpu cooling support"
>>  	depends on THERMAL_OF
>>  	help
>> +	  Enable the CPU cooling features. If the system has no active
>> +	  cooling device available, this option allows to use the CPU
>> +	  as a cooling device.
>> +
>> +choice
>> +	prompt "CPU cooling strategies"
>> +	depends on CPU_THERMAL
>> +	default CPU_FREQ_THERMAL
>> +	help
>> +	  Select the CPU cooling strategy.
>> +
>> +config CPU_FREQ_THERMAL
>> +        bool "CPU frequency cooling strategy"
>> +	depends on CPU_FREQ
>> +	help
>>  	  This implements the generic cpu cooling mechanism through frequency
>>  	  reduction. An ACPI version of this already exists
>>  	  (drivers/acpi/processor_thermal.c).
>>  	  This will be useful for platforms using the generic thermal interface
>>  	  and not the ACPI interface.
>>  
>> -	  If you want this support, you should say Y here.
> 
> Should this line be moved to the CPU_THERMAL section above ?
> 

Probably, I will double check it.

[ ... ]

>> -#endif	/* CONFIG_CPU_THERMAL */
>> +#endif	/* CONFIG_CPU_FREQ_THERMAL */
>>  
>>  #endif /* __CPU_COOLING_H__ */
> 
> drivers/cpufreq/Kconfig:        # if CPU_THERMAL is on and THERMAL=m, CPUFREQ_DT cannot be =y:
> drivers/cpufreq/Kconfig:        depends on !CPU_THERMAL || THERMAL
> drivers/cpufreq/Kconfig:        depends on !CPU_THERMAL || THERMAL
> drivers/cpufreq/Kconfig.arm:    # if CPU_THERMAL is on and THERMAL=m, ARM_BIT_LITTLE_CPUFREQ cannot be =y
> drivers/cpufreq/Kconfig.arm:    depends on !CPU_THERMAL || THERMAL
> drivers/cpufreq/Kconfig.arm:    depends on !CPU_THERMAL || THERMAL
> 
> All of these need to use CPU_FREQ_THERMAL now>
> include/trace/events/thermal.h:#ifdef CONFIG_CPU_THERMAL
> include/trace/events/thermal.h:#endif /* CONFIG_CPU_THERMAL */

Ok.

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