Re: [PATCH v2 4/9] of: Add bindings of hw throttle for soctherm

[Eduardo Valentin]

From: Eduardo Valentin <edubezval@xxxxxxxxx>
To: Wei Ni <wni@xxxxxxxxxx>
Cc: thierry.reding@xxxxxxxxx, robh+dt@xxxxxxxxxx, rui.zhang@xxxxxxxxx,
	MLongnecker@xxxxxxxxxx, swarren@xxxxxxxxxxxxx,
	mikko.perttunen@xxxxxxxx, linux-tegra@xxxxxxxxxxxxxxx,
	linux-pm@xxxxxxxxxxxxxxx, devicetree@xxxxxxxxxxxxxxx,
	linux-kernel@xxxxxxxxxxxxxxx
Bcc: 
Subject: Re: [PATCH v2 4/9] of: Add bindings of hw throttle for soctherm
Reply-To: 
In-Reply-To: <1461727554-15065-5-git-send-email-wni@xxxxxxxxxx>

The patch title must say something about the fact that this is specific
to nvidia thermal driver.

On Wed, Apr 27, 2016 at 11:25:49AM +0800, Wei Ni wrote:
> Add HW throttle configuration sub-node for soctherm, which
> is used to describe the throttle event, and worked as a
> cooling device. The "hot" type trip in thermal zone can
> be bound to this cooling device, and trigger the throttle
> function.
> 
> Signed-off-by: Wei Ni <wni@xxxxxxxxxx>
> ---
>  .../bindings/thermal/nvidia,tegra124-soctherm.txt  | 89 +++++++++++++++++++++-
>  1 file changed, 87 insertions(+), 2 deletions(-)
> 
> diff --git a/Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt b/Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt
> index edebfa0a985e..dc337d139f49 100644
> --- a/Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt
> +++ b/Documentation/devicetree/bindings/thermal/nvidia,tegra124-soctherm.txt
> @@ -10,8 +10,14 @@ Required properties :
>  - compatible : For Tegra124, must contain "nvidia,tegra124-soctherm".
>    For Tegra132, must contain "nvidia,tegra132-soctherm".
>    For Tegra210, must contain "nvidia,tegra210-soctherm".
> -- reg : Should contain 1 entry:
> +- reg : Should contain at least 2 entries for each entry in reg-names:
>    - SOCTHERM register set
> +  - Tegra CAR register set: Required for Tegra124 and Tegra210.
> +  - CCROC register set: Required for Tegra132.
> +- reg-names :  Should contain at least 2 entries:
> +  - soctherm-reg
> +  - car-reg
> +  - ccroc-reg
>  - interrupts : Defines the interrupt used by SOCTHERM
>  - clocks : Must contain an entry for each entry in clock-names.
>    See ../clocks/clock-bindings.txt for details.
> @@ -25,17 +31,44 @@ Required properties :
>  - #thermal-sensor-cells : Should be 1. See ./thermal.txt for a description
>      of this property. See <dt-bindings/thermal/tegra124-soctherm.h> for a
>      list of valid values when referring to thermal sensors.
> +- throttle-cfgs: A sub-node which is a container of configuration for each
> +    hardware throttle events. These events can be set as cooling devices.
> +  * throttle events: Sub-nodes must be named as "light" or "heavy".
> +      Properties:
> +      - priority: Each throttles has its own throttle settings, so the SW need
> +        to set priorities for various throttle, the HW arbiter can select the
> +        final throttle settings.
> +        Bigger value indicates higher priority, In general, higher priority
> +        translates to lower target frequency. SW needs to ensure that critical
> +        thermal alarms are given higher priority, and ensure that there is
> +        no race if priority of two vectors is set to the same value.
> +      - cpu-throt-depth:  This property is for Tegra124 and Tegra210. It is
> +        the throttling depth of pulse skippers, it's the percentage
> +        throttling.
> +      - cpu-throt-level: This property is only for Tegra132, it is the level
> +        of pulse skippers, which used to throttle clock frequencies. It
> +        indicates cpu clock throttling depth, and the depth can be programmed.
> +        Must set as following values:
> +        TEGRA_SOCTHERM_THROT_LEVEL_LOW, TEGRA_SOCTHERM_THROT_LEVEL_MED
> +        TEGRA_SOCTHERM_THROT_LEVEL_HIGH, TEGRA_SOCTHERM_THROT_LEVEL_NONE

These properties are not generic properties. My understanding is that
you must have vendor prefix in such case. Same applies to the new nodes.

> +      - #cooling-cells: Should be 1. This cooling device only support on/off state.
> +        See ./thermal.txt for a description of this property.
>  
>  Note:
>  - the "critical" type trip points will be set to SOC_THERM hardware as the
>  shut down temperature. Once the temperature of this thermal zone is higher
>  than it, the system will be shutdown or reset by hardware.
> +- the "hot" type trip points will be set to SOC_THERM hardware as the throttle
> +temperature. Once the the temperature of this thermal zone is higher
> +than it, it will trigger the HW throttle event.
>  
>  Example :
>  
>  	soctherm@700e2000 {
>  		compatible = "nvidia,tegra124-soctherm";
> -		reg = <0x0 0x700e2000 0x0 0x1000>;
> +		reg = <0x0 0x700e2000 0x0 0x600  /* SOC_THERM reg_base */
> +			0x0 0x60006000 0x0 0x400 /* CAR reg_base */
> +		reg-names = "soctherm-reg", "car-reg";
>  		interrupts = <GIC_SPI 48 IRQ_TYPE_LEVEL_HIGH>;
>  		clocks = <&tegra_car TEGRA124_CLK_TSENSOR>,
>  			<&tegra_car TEGRA124_CLK_SOC_THERM>;
> @@ -44,6 +77,45 @@ Example :
>  		reset-names = "soctherm";
>  
>  		#thermal-sensor-cells = <1>;
> +
> +		throttle-cfgs {
> +			throttle_heavy: heavy {
> +				priority = <100>;
> +				cpu-throt-depth = <85>;
> +
> +				#cooling-cells = <1>;
> +			};
> +			throttle_light: light {
> +				priority = <80>;
> +				cpu-throt-depth = <50>;
> +
> +				#cooling-cells = <1>;
> +			};
> +		};

This is a sensor, which at the same time, has sub nodes that can be
cooling devices. Is my understanding correct of what you are trying to
do?


> +	};
> +
> +Example: referring to Tegra132's "reg", "reg-names" and "throttle-cfgs" :
> +
> +	soctherm@0,700e2000 {
> +		compatible = "nvidia,tegra132-soctherm";
> +		reg = <0x0 0x700e2000 0x0 0x600  /* SOC_THERM reg_base */
> +			0x0 0x70040000 0x0 0x200>; /* CCROC reg_base */;
> +		reg-names = "soctherm-reg", "ccroc-reg";
> +
> +		throttle-cfgs {
> +			throttle_heavy: heavy {
> +				priority = <100>;
> +				cpu-throt-level = <TEGRA_SOCTHERM_THROT_LEVEL_HIGH>;
> +
> +				#cooling-cells = <1>;
> +			};
> +			throttle_light: light {
> +				priority = <80>;
> +				cpu-throt-level = <TEGRA_SOCTHERM_THROT_LEVEL_MED>;
> +
> +				#cooling-cells = <1>;

Could you please describe a little here what to expect of the above
setup?


> +			};
> +		};
>  	};
>  
>  Example: referring to thermal sensors :
> @@ -62,6 +134,19 @@ Example: referring to thermal sensors :
>  					hysteresis = <1000>;
>  					type = "critical";
>  				};
> +
> +				cpu_throttle_trip: throttle-trip {
> +					temperature = <100000>;
> +					hysteresis = <1000>;
> +					type = "hot";
> +				};
> +			};
> +
> +			cooling-maps {
> +				map0 {
> +					trip = <&cpu_throttle_trip>;
> +					cooling-device = <&throttle_heavy 1 1>;
> +				};
>  			};
>                  };
>  	};
> -- 
> 1.9.1
>