Re: [RFC PATCH 01/14] cpufreq: cpufreq-cpu0: add dt node parsing for 'cooling-zones'

[Eduardo Valentin <eduardo.valentin@ti.com>]

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Hey Mark,

On 27-08-2013 05:29, Mark Rutland wrote:
> On Sat, Aug 24, 2013 at 12:15:42AM +0100, Eduardo Valentin wrote:
>> This patch changes the cpufreq-cpu0 driver to consider if
>> a cpu needs cooling (with cpufreq). In case the cooling is needed,
>> it can be flagged at the cpu0 device tree node, with the list
>> of zones property 'cooling-zones'.
>>
>> In case this list of zones is present, the driver will
>> load a cpufreq cooling device in the system. The cpufreq-cpu0
>> driver is not interested in determining how the system should
>> be using the cooling device. The driver is responsible
>> only of loading the cooling device.
>>
>> Describing how the cooling device will be used can be
>> accomplished by setting up a thermal zone that references
>> and is composed by the cpufreq cooling device.
>>
>> Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
>> Cc: Viresh Kumar <viresh.kumar@linaro.org>
>> Cc: Grant Likely <grant.likely@linaro.org>
>> Cc: Rob Herring <rob.herring@calxeda.com>
>> Cc: cpufreq@vger.kernel.org
>> Cc: linux-pm@vger.kernel.org
>> Cc: linux-kernel@vger.kernel.org
>> Cc: devicetree-discuss@lists.ozlabs.org
>> Signed-off-by: Eduardo Valentin <eduardo.valentin@ti.com>
>> ---
>>  Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt |  4 ++++
>>  drivers/cpufreq/cpufreq-cpu0.c                             | 12 ++++++++++++
>>  2 files changed, 16 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt b/Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt
>> index 051f764..add50f7 100644
>> --- a/Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt
>> +++ b/Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt
>> @@ -15,6 +15,9 @@ Optional properties:
>>  - clock-latency: Specify the possible maximum transition latency for clock,
>>    in unit of nanoseconds.
>>  - voltage-tolerance: Specify the CPU voltage tolerance in percentage.
>> +- cooling-zones: A list of thermal zones phandles. The generic cpu
>> +  cooling (freq clipping) is loaded by the generic cpufreq-cpu0 driver
>> +  in case the device tree node has this list.
> 
> Bindings should not describe the behaviour of any kernel (and for that
> reason I'm not very keen on the current cpufreq-cpu0 binding document).
> 

Right.

> Bindings should simply describe the hardware. This addition could
> instead be:
> 
>  - cooling-zones: a list of thermal zone phandles.
> 

OK. This works for me.

> However, as the thermal zone binding doesn't seem to have appeared by
> this patch, it should get moved later anyway...

Yeah, I will reorder them.

> 
> Thanks,
> Mark.
> 
>>  
>>  Examples:
>>  
>> @@ -33,6 +36,7 @@ cpus {
>>  			198000  850000
>>  		>;
>>  		clock-latency = <61036>; /* two CLK32 periods */
>> +		cooling-zones = <&cpu_thermal>;
>>  	};
>>  
>>  	cpu@1 {
>> diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c
>> index ad1fde2..ede6487 100644
>> --- a/drivers/cpufreq/cpufreq-cpu0.c
>> +++ b/drivers/cpufreq/cpufreq-cpu0.c
>> @@ -20,6 +20,9 @@
>>  #include <linux/platform_device.h>
>>  #include <linux/regulator/consumer.h>
>>  #include <linux/slab.h>
>> +#include <linux/thermal.h>
>> +#include <linux/cpu_cooling.h>
>> +#include <linux/cpumask.h>
>>  
>>  static unsigned int transition_latency;
>>  static unsigned int voltage_tolerance; /* in percentage */
>> @@ -28,6 +31,7 @@ static struct device *cpu_dev;
>>  static struct clk *cpu_clk;
>>  static struct regulator *cpu_reg;
>>  static struct cpufreq_frequency_table *freq_table;
>> +static struct thermal_cooling_device *cdev;
>>  
>>  static int cpu0_verify_speed(struct cpufreq_policy *policy)
>>  {
>> @@ -268,6 +272,13 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
>>  		goto out_free_table;
>>  	}
>>  
>> +	/*
>> +	 * For now, just loading the cooling device;
>> +	 * thermal DT code takes care of matching them.
>> +	 */
>> +	if (of_find_property(np, "cooling-zones", NULL))
>> +		cdev = cpufreq_cooling_register(cpu_present_mask);
>> +
>>  	of_node_put(np);
>>  	of_node_put(parent);
>>  	return 0;
>> @@ -283,6 +294,7 @@ out_put_parent:
>>  
>>  static int cpu0_cpufreq_remove(struct platform_device *pdev)
>>  {
>> +	cpufreq_cooling_unregister(cdev);
>>  	cpufreq_unregister_driver(&cpu0_cpufreq_driver);
>>  	opp_free_cpufreq_table(cpu_dev, &freq_table);
>>  
>> -- 
>> 1.8.2.1.342.gfa7285d
>>
>>
> 
> 


-- 
You have got to be excited about what you are doing. (L. Lamport)

Eduardo Valentin


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