Date: Wed, 4 Nov 2015 10:56:34 -0800
From: Eduardo Valentin <edubezval@gmail.com>
To: Javi Merino <javi.merino@arm.com>
Cc: linux-pm@vger.kernel.org, linux-kernel@vger.kernel.org, rui.zang@intel.com,
        Zhang Rui <rui.zhang@intel.com>
Subject: Re: [PATCH v2 2/3] thermal: of: parse stacked thermal zones from
 device tree
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On Wed, Nov 04, 2015 at 05:37:41PM +0000, Javi Merino wrote:
> Let device tree set thermal zones in the thermal-sensors list of
> phandles and set up the thermal zone hierarchy based on the information
> present there.
> 
> Cc: Zhang Rui <rui.zhang@intel.com>
> Cc: Eduardo Valentin <edubezval@gmail.com>
> Signed-off-by: Javi Merino <javi.merino@arm.com>
> ---
>  .../devicetree/bindings/thermal/thermal.txt        | 154 ++++++++++++++++++++-
>  drivers/thermal/of-thermal.c                       |  99 +++++++++++++

Please split this patch.

>  2 files changed, 250 insertions(+), 3 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/thermal/thermal.txt b/Documentation/devicetree/bindings/thermal/thermal.txt
> index 41b817f7b670..52b7e9ae3b4d 100644
> --- a/Documentation/devicetree/bindings/thermal/thermal.txt
> +++ b/Documentation/devicetree/bindings/thermal/thermal.txt
> @@ -145,9 +145,12 @@ Required properties:
>    Size: one cell
>  
>  - thermal-sensors:	A list of thermal sensor phandles and sensor specifier
> -  Type: list of 	used while monitoring the thermal zone.
> -  phandles + sensor
> -  specifier
> +  Type: list of 	used while monitoring the thermal zone. The phandles
> +  phandles + sensor	can point to thermal sensors or other thermal zone
> +  specifier		nodes. If it points to other thermal zone
> +			nodes you should omit the sensor specifier
> +			and set #thermal-sensor-cells to 0 for the
> +			thermal zone.
>  
>  - trips:		A sub-node which is a container of only trip point nodes
>    Type: sub-node	required to describe the thermal zone.
> @@ -603,3 +606,148 @@ thermal-zones {
>  The above example is a mix of previous examples, a sensor IP with several internal
>  sensors used to monitor different zones, one of them is composed by several sensors and
>  with different cooling devices.
> +
> +(e) Board thermal with stacked thermal zones
> +
> +Instead of setting up one thermal zone combining multiple thermal
> +zones and multiple trip points for each cooling device, we can create
> +a hierarchy of thermal zones.
> +
> +#include <dt-bindings/thermal/thermal.h>
> +
> +&i2c1 {
> +	...
> +	/*
> +	 * An IC with several temperature sensor.
> +	 */
> +	adc_dummy: sensor@0x50 {
> +		...
> +		#thermal-sensor-cells = <1>; /* sensor internal ID */
> +	};
> +};
> +
> +thermal-zones {
> +
> +        cpu_thermal: cpu_thermal {
> +		polling-delay-passive = <1000>; /* milliseconds */
> +		polling-delay = <2500>; /* milliseconds */
> +
> +		sustainable-power = <2500>;
> +
> +		thermal-sensors = <&adc_dummy 0>
> +
> +		trips {
> +			cpu_trip: cpu-trip {
> +				temperature = <60000>; /* millicelsius */
> +				hysteresis = <2000>; /* millicelsius */
> +				type = "passive";
> +			};
> +                };
> +
> +		cooling-maps {
> +			map0 {
> +				trip = <&cpu_trip>;
> +				cooling-device = <&cpu0 0 2>;
> +			};
> +                };
> +        };
> +
> +        gpu_thermal: gpu_thermal {
> +		polling-delay-passive = <1000>; /* milliseconds */
> +		polling-delay = <2500>; /* milliseconds */
> +
> +		sustainable-power = <2500>;
> +
> +		thermal-sensors = <&adc_dummy 2>
> +
> +		trips {
> +			gpu_trip: gpu-trip {
> +				temperature = <55000>; /* millicelsius */
> +				hysteresis = <2000>; /* millicelsius */
> +				type = "passive";
> +			}
> +                };
> +
> +		cooling-maps {
> +			map0 {
> +				trip = <&gpu_trip>;
> +				cooling-device = <&gpu0 0 2>;
> +			};
> +                };
> +        };
> +
> +        lcd_thermal: lcd_thermal {
> +		polling-delay-passive = <1000>; /* milliseconds */
> +		polling-delay = <2500>; /* milliseconds */
> +
> +		sustainable-power = <2500>;
> +
> +		thermal-sensors = <&adc_dummy 1>
> +
> +		trips {
> +			lcd_trip: lcp-trip {
> +				temperature = <53000>; /* millicelsius */
> +				hysteresis = <2000>; /* millicelsius */
> +				type = "passive";
> +			};
> +                };
> +
> +		cooling-maps {
> +			map0 {
> +				trip = <&lcd_trip>;
> +				cooling-device = <&lcd0 5 10>;
> +			};
> +                };
> +        };
> +
> +	board_thermal: board-thermal {
> +		polling-delay-passive = <1000>; /* milliseconds */
> +		polling-delay = <2500>; /* milliseconds */
> +
> +		thermal-sensors = <&cpu_thermal &gpu_thermal &lcd_thermal>
> +

(no, I have not grepped the device tree)
Was there any other occurrence of such construction ?

It just looks awkward that one property holds two types of data. Is DT
strongly typed?

I would say, following the DT pattern, one would expect to have the
binding to allow one thermal zone to be written inside another thermal
zone, no?

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