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Date: Tue, 27 Aug 2013 09:05:48 -0400
From: Eduardo Valentin <eduardo.valentin@...com>
To: Mark Rutland <mark.rutland@....com>
CC: Eduardo Valentin <eduardo.valentin@...com>,
"swarren@...dotorg.org" <swarren@...dotorg.org>,
Pawel Moll <Pawel.Moll@....com>,
"ian.campbell@...rix.com" <ian.campbell@...rix.com>,
"grant.likely@...aro.org" <grant.likely@...aro.org>,
"rob.herring@...xeda.com" <rob.herring@...xeda.com>,
"linux@...ck-us.net" <linux@...ck-us.net>,
"rui.zhang@...el.com" <rui.zhang@...el.com>,
"wni@...dia.com" <wni@...dia.com>,
"durgadoss.r@...el.com" <durgadoss.r@...el.com>,
"linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"lm-sensors@...sensors.org" <lm-sensors@...sensors.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"Rafael J. Wysocki" <rjw@...k.pl>,
Viresh Kumar <viresh.kumar@...aro.org>,
"cpufreq@...r.kernel.org" <cpufreq@...r.kernel.org>,
"devicetree-discuss@...ts.ozlabs.org"
<devicetree-discuss@...ts.ozlabs.org>
Subject: Re: [RFC PATCH 01/14] cpufreq: cpufreq-cpu0: add dt node parsing
for 'cooling-zones'
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@...k.pl>
>> Cc: Viresh Kumar <viresh.kumar@...aro.org>
>> Cc: Grant Likely <grant.likely@...aro.org>
>> Cc: Rob Herring <rob.herring@...xeda.com>
>> Cc: cpufreq@...r.kernel.org
>> Cc: linux-pm@...r.kernel.org
>> Cc: linux-kernel@...r.kernel.org
>> Cc: devicetree-discuss@...ts.ozlabs.org
>> Signed-off-by: Eduardo Valentin <eduardo.valentin@...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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