Re: [PATCH V4 1/2] dt-bindings: thermal: add support for Broadcom's Northstar thermal

[Eduardo Valentin <edubezval@gmail.com>]

Rafal,

On Fri, Mar 31, 2017 at 10:11:23PM +0200, Rafał Miłecki wrote:
> From: Rafał Miłecki <rafal@milecki.pl>
> 
> This commit documents binding for thermal used in Northstar family SoCs.
> 
> Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
> ---
> V3: Add thermal-zones to the example
>     Rob: Because of this update, I didn't include Acked-by I got for V2
> ---
>  .../devicetree/bindings/thermal/brcm,ns-thermal    | 26 ++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/thermal/brcm,ns-thermal
> 
> diff --git a/Documentation/devicetree/bindings/thermal/brcm,ns-thermal b/Documentation/devicetree/bindings/thermal/brcm,ns-thermal
> new file mode 100644
> index 000000000000..c561c7349f17
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/thermal/brcm,ns-thermal
> @@ -0,0 +1,26 @@
> +* Broadcom Northstar Thermal
> +
> +This binding describes thermal sensor that is part of Northstar's DMU (Device
> +Management Unit).
> +
> +Required properties:
> +- compatible : Must be "brcm,ns-thermal"
> +- reg : iomem address range of PVTMON registers
> +- #thermal-sensor-cells : Should be <0>
> +
> +Example:
> +
> +thermal: thermal@1800c2c0 {
> +	compatible = "brcm,ns-thermal";
> +	reg = <0x1800c2c0 0x10>;
> +	#thermal-sensor-cells = <0>;
> +};
> +
> +thermal-zones {
> +	cpu_thermal: cpu-thermal {
> +		polling-delay-passive = <0>;
> +		polling-delay = <1000>;
> +		coefficients = <(-556) 418000>;
> +		thermal-sensors = <&thermal>;

You need to define trips and cooling devices here. Otherwise, makes
little sense to have this device in thermal subsystem. Here is an
example of minimal set:
https://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux-soc-thermal.git/commit/?h=linus&id=1e2ac9821de6a85d3e8358f238436708d1d46869

The above has no passive action. It is just gonna shutdown the system if
temperature crosses a threshold. 

But, a typical cooling device would be CPU frequency throttling. Do you have
that up and running in your routers?

> +	};
> +};
> -- 
> 2.11.0
>