linux-kernel - Re: [RESEND PATCH V1 1/9] cpufreq: cpufreq-cpu0: add dt node parsing for 'needs-cooling'

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Date:	Fri, 26 Jul 2013 01:28:36 +0200
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Eduardo Valentin <eduardo.valentin@...com>
Cc:	devicetree-discuss@...ts.ozlabs.org, wni@...dia.com,
	l.stach@...gutronix.de, linux-kernel@...r.kernel.org,
	linux-pm@...r.kernel.org, lm-sensors@...sensors.org,
	Viresh Kumar <viresh.kumar@...aro.org>,
	Grant Likely <grant.likely@...aro.org>,
	Rob Herring <rob.herring@...xeda.com>, cpufreq@...r.kernel.org
Subject: Re: [RESEND PATCH V1 1/9] cpufreq: cpufreq-cpu0: add dt node parsing for 'needs-cooling'

On Wednesday, July 17, 2013 11:17:20 AM 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 boolean
> property 'needs-cooling'.
> 
> In case this boolean 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>

FWIW, this change is fine by me, but I guess it should be handled along with
the entire series.

> 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 | 3 +++
>  drivers/cpufreq/cpufreq-cpu0.c                             | 8 ++++++++
>  2 files changed, 11 insertions(+)
> 
> diff --git a/Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt b/Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt
> index 051f764..e8ff916 100644
> --- a/Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt
> +++ b/Documentation/devicetree/bindings/cpufreq/cpufreq-cpu0.txt
> @@ -15,6 +15,8 @@ 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.
> +- needs-cooling: The generic cpu cooling (freq clipping) is loaded by the
> +generic cpufreq-cpu0 driver in case the device tree node has this boolean.
>  
>  Examples:
>  
> @@ -33,6 +35,7 @@ cpus {
>  			198000  850000
>  		>;
>  		clock-latency = <61036>; /* two CLK32 periods */
> +		needs-cooling;
>  	};
>  
>  	cpu@1 {
> diff --git a/drivers/cpufreq/cpufreq-cpu0.c b/drivers/cpufreq/cpufreq-cpu0.c
> index ad1fde2..4a8747a 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 +272,9 @@ static int cpu0_cpufreq_probe(struct platform_device *pdev)
>  		goto out_free_table;
>  	}
>  
> +	if (of_property_read_bool(np, "needs-cooling"))
> +		cdev = cpufreq_cooling_register(cpu_present_mask);
> +
>  	of_node_put(np);
>  	of_node_put(parent);
>  	return 0;
> @@ -283,6 +290,7 @@ 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);
>  
> 
-- 
I speak only for myself.
Rafael J. Wysocki, Intel Open Source Technology Center.
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