linux-kernel - Re: [PATCH v5 1/6] Documentation: dts: Documentation entry to explain how to use PWM FAN as a cooling device

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Message-ID: <20150225191123.GA2950@developer.amazonguestwifi.org>
Date:	Wed, 25 Feb 2015 15:11:24 -0400
From:	Eduardo Valentin <edubezval@...il.com>
To:	Lukasz Majewski <l.majewski@...sung.com>
Cc:	Kamil Debski <k.debski@...sung.com>,
	Jean Delvare <jdelvare@...e.de>,
	Guenter Roeck <linux@...ck-us.net>,
	Kukjin Kim <kgene@...nel.org>, lm-sensors@...sensors.org,
	Linux PM list <linux-pm@...r.kernel.org>,
	"linux-samsung-soc@...r.kernel.org" 
	<linux-samsung-soc@...r.kernel.org>, devicetree@...r.kernel.org,
	Lukasz Majewski <l.majewski@...ess.pl>,
	Kukjin Kim <kgene.kim@...sung.com>,
	linux-kernel@...r.kernel.org,
	Sjoerd Simons <sjoerd.simons@...labora.co.uk>,
	Abhilash Kesavan <kesavan.abhilash@...il.com>,
	Abhilash Kesavan <a.kesavan@...sung.com>
Subject: Re: [PATCH v5 1/6] Documentation: dts: Documentation entry to
 explain how to use PWM FAN as a cooling device

On Wed, Feb 25, 2015 at 04:34:17PM +0100, Lukasz Majewski wrote:
> Explanation of several properties, which allow PWM fan working as a cooling
> device, have been embraced in this commit.
> 
> Signed-off-by: Lukasz Majewski <l.majewski@...sung.com>
> ---
> Changes for v2:
> - Rename cooling-pwm-values to cooling-levels
> - Remove default-pulse-width property and stick to default hwmon policy
> Changes for v3:
> - Changing commit title from "hwmon: dts: Doc:" to "Documentation: dts"
> - Remove unnecessary properties
> - Set maximal cooling level to 230 instead of 255
> Changes for v4:
> - None
> Changes for v5:
> - Move thermal-zones description to example section
> - Extending example section
> 
> ---
>  .../devicetree/bindings/hwmon/pwm-fan.txt          | 25 +++++++++++++++++++++-
>  1 file changed, 24 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/devicetree/bindings/hwmon/pwm-fan.txt b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
> index 610757c..645251b 100644
> --- a/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
> +++ b/Documentation/devicetree/bindings/hwmon/pwm-fan.txt
> @@ -3,10 +3,33 @@ Bindings for a fan connected to the PWM lines
>  Required properties:
>  - compatible	: "pwm-fan"
>  - pwms		: the PWM that is used to control the PWM fan
> +- cooling-levels      : PWM duty cycle values in a range from 0 to 255
> +			which correspond to thermal cooling states
>  
>  Example:
> -	pwm-fan {
> +	fan0: pwm-fan {
>  		compatible = "pwm-fan";
>  		status = "okay";
>  		pwms = <&pwm 0 10000 0>;
> +		cooling-levels = <0 102 170 230>;
> +	};
> +
> +	thermal-zones {
> +		cpu_thermal: cpu-thermal {
> +		cooling-min-state = <0>;
> +		cooling-max-state = <3>;
> +		#cooling-cells = <2>;
> +		trips {
> +			cpu_alert1: cpu-alert1 {
> +				temperature = <100000>; /* millicelsius */
> +				hysteresis = <2000>; /* millicelsius */
> +				type = "passive";
> +			};
> +		};
> +		cooling-maps {
> +			map0 {
> +			     trip = <&cpu_alert1>;
> +			     cooling-device = <&fan0 0 1>;
> +			};
> +		};

The above example has two issues:
(1) it is wrong, as the cooling device properties are in the thermal
zone node.
(2) has a misalignment / tabulation

Can you please fix that in your next version too?

>  	};
> -- 
> 2.0.0.rc2
> 

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