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Message-ID: <CAHLCerMB2Nde-Gre+2pyNcd3AW2kDPSgo8KqON4V5vMUXZN1kw@mail.gmail.com>
Date: Thu, 5 Mar 2020 02:32:47 +0530
From: Amit Kucheria <amit.kucheria@...aro.org>
To: Rob Herring <robh@...nel.org>
Cc: "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
linux-arm-msm <linux-arm-msm@...r.kernel.org>,
Stephen Boyd <swboyd@...omium.org>,
Matthias Kaehlcke <mka@...omium.org>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Zhang Rui <rui.zhang@...el.com>,
"open list:THERMAL" <linux-pm@...r.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@...r.kernel.org>
Subject: Re: [RFC PATCH v1 3/3] dt-bindings: thermal: Add yaml bindings for
thermal zones
On Tue, Feb 25, 2020 at 3:24 AM Rob Herring <robh@...nel.org> wrote:
>
> On Mon, Feb 24, 2020 at 1:26 AM Amit Kucheria <amit.kucheria@...aro.org> wrote:
> >
> > As part of moving the thermal bindings to YAML, split it up into 3
> > bindings: thermal sensors, cooling devices and thermal zones.
> >
> > The thermal-zone binding is a software abstraction to capture the
> > properties of each zone - how often they should be checked, the
> > temperature thresholds (trips) at which mitigation actions need to be
> > taken and the level of mitigation needed at those thresholds.
> >
> > Signed-off-by: Amit Kucheria <amit.kucheria@...aro.org>
> > ---
> > .../bindings/thermal/thermal-zones.yaml | 302 ++++++++++++++++++
> > 1 file changed, 302 insertions(+)
> > create mode 100644 Documentation/devicetree/bindings/thermal/thermal-zones.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/thermal/thermal-zones.yaml b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
> > new file mode 100644
> > index 000000000000..bc1ce8e41324
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml
> > @@ -0,0 +1,302 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR MIT)
>
> Why MIT instead of BSD-2-Clause? And do you have rights to add that?
> Any text you copied over from the .txt file was only GPL2. Relicensing
> would be nice if you can get permission from the authors.
Changed back to GPL2. I will send out a separate email to get
permission for relicensing the bindings.
> > +# Copyright 2020 Linaro Ltd.
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/thermal/thermal-zones.yaml#
> > +$schema: http://devicetree.org/meta-schemas/base.yaml#
> > +
> > +title: Thermal zone binding
> > +
> > +maintainers:
> > + - Amit Kucheria <amitk@...nel.org>
> > +
> > +description: |
> > + Thermal management is achieved in devicetree by describing the sensor hardware
> > + and the software abstraction of cooling devices and thermal zones required to
> > + take appropriate action to mitigate thermal overloads.
> > +
> > + The following node types are used to completely describe a thermal management
> > + system in devicetree:
> > + - thermal-sensor: device that measures temperature, has SoC-specific bindings
> > + - cooling-device: device used to dissipate heat either passively or artively
>
> typo
Fixed.
>
> > + - thermal-zones: a container of the following node types used to describe all
> > + thermal data for the platform
> > +
> > + This binding describes the thermal-zones.
> > +
> > + The polling-delay properties of a thermal-zone are bound to the maximum dT/dt
> > + (temperature derivative over time) in two situations for a thermal zone:
> > + 1. when passive cooling is activated (polling-delay-passive)
> > + 2. when the zone just needs to be monitored (polling-delay) or when
> > + active cooling is activated.
> > +
> > + The maximum dT/dt is highly bound to hardware power consumption and
> > + dissipation capability. The delays should be chosen to account for said
> > + max dT/dt, such that a device does not cross several trip boundaries
> > + unexpectedly between polls. Choosing the right polling delays shall avoid
> > + having the device in temperature ranges that may damage the silicon structures
> > + and reduce silicon lifetime.
> > +
> > +properties:
> > + thermal-zones:
> > + type: object
> > + description:
> > + A /thermal-zones node is required in order to use the thermal framework to
> > + manage input from the various thermal zones in the system in order to
> > + mitigate thermal overload conditions. It does not represent a real device
> > + in the system, but acts as a container to link thermal sensor devices,
> > + platform-data regarding temperature thresholds and the mitigation actions
> > + to take when the temperature crosses those thresholds.
> > +
> > + properties:
> > + $nodename:
> > + pattern: "^[a-zA-Z][a-zA-Z0-9,\\-]{1,12}-thermal$"
> > + type: object
> > + description:
> > + Each thermal zone node contains information about how frequently it
> > + must be checked, the sensor responsible for reporting temperature for
> > + this zone, one sub-node containing the various trip points for this
> > + zone and one sub-node containing all the zone cooling-maps.
> > +
> > + properties:
> > + polling-delay:
> > + $ref: /schemas/types.yaml#/definitions/uint32
> > + minimum: 0
> > + description:
> > + The maximum number of milliseconds to wait between polls when
> > + checking this thermal zone. Setting this to 0 disables the polling
> > + timers setup by the thermal framework and assumes that the thermal
> > + sensors in this zone support interrupts.
> > +
> > + polling-delay-passive:
> > + $ref: /schemas/types.yaml#/definitions/uint32
> > + minimum: 0
> > + description:
> > + The maximum number of milliseconds to wait between polls when
> > + checking this thermal zone while doing passive cooling. Setting
> > + this to 0 disables the polling timers setup by the thermal
> > + framework and assumes that the thermal sensors in this zone
> > + support interrupts.
> > +
> > + thermal-sensors:
> > + $ref: /schemas/types.yaml#/definitions/phandle-array
> > + description:
> > + A list of thermal sensor phandles and sensor specifiers used to
> > + monitor this thermal zone.
> > +
> > + trips:
> > + type: object
> > + description:
> > + This node describes a set of points in the temperature domain at
> > + which the thermal framework needs to takes action. The actions to
> > + be taken are defined in another node called cooling-maps.
> > +
> > + patternProperties:
> > + "^[a-zA-Z][a-zA-Z0-9,+\\._]{0,63}$":
> > + type: object
> > +
> > + properties:
> > + temperature:
> > + $ref: /schemas/types.yaml#/definitions/int32
> > + description:
> > + An integer expressing the trip temperature in millicelsius.
>
> Wouldn't 200000 mC be a reasonable max? And -273000 mC min.
It would indeed. :-)
> > +
> > + hysteresis:
> > + $ref: /schemas/types.yaml#/definitions/uint32
> > + description:
> > + An unsigned integer expressing the hysteresis delta with
> > + respect to the trip temperature property above, also in
> > + millicelsius.
> > +
> > + type:
> > + oneOf:
> > + - items:
> > + - enum:
>
> Drop oneOf and items. Just enum is enough.
Fixed.
>
> > + - active
> > + - passive
> > + - hot
> > + - critical
> > + description: |
> > + There are four valid trip types,
> > + - active - enable active cooling e.g. fans
> > + - passive - enable passive cooling e.g. throttling cpu
> > + - hot - send notification to driver if .notify
> > + callback registered
> > + - critical - send notification to driver if .notify
> > + callback registered and trigger a shutdown
>
> Perhaps make these comments on each enum entry.
I've moved the one-line descriptions to comments before each enum
entry. However, I ended up adding more detailed descriptions in the
description sections because I felt these are not well-defined in
documentation. Let me know what you think.
> > +
> > + required:
> > + - temperature
> > + - hysteresis
> > + - type
>
> 'additionalProperties: false'? Or can the node have other properties?
Added.
> > +
> > + cooling-maps:
> > + type: object
> > + description:
> > + This node describes the action to be taken when a thermal zone
> > + crosses one of the temperature thresholds described in the trips
> > + node. The action takes the form of a mapping relation between a
> > + trip and the target cooling device state.
> > +
> > + patternProperties:
> > + "^map[0-9][-a-zA-Z0-9]*$":
> > + type: object
> > +
> > + properties:
> > + trip:
> > + $ref: /schemas/types.yaml#/definitions/phandle
> > + description:
> > + A phandle of a trip point node within this thermal zone.
> > +
> > + cooling-device:
> > + $ref: /schemas/types.yaml#/definitions/phandle-array
> > + description:
> > + A list of cooling device phandles along with the minimum
> > + and maximum cooling state specifiers for each cooling
> > + device. Using the THERMAL_NO_LIMIT (-1UL) constant in the
> > + cooling-device phandle limit specifier lets the framework
> > + use the minimum and maximum cooling state for that cooling
> > + device automatically.
> > +
> > + contribution:
> > + $ref: /schemas/types.yaml#/definitions/uint32
> > + minimum: 0
> > + maximum: 100
> > + description:
> > + The contribution of the cooling devices at the trip
> > + temperature, both referenced in this map, to this thermal
> > + zone as a percentage.
> > +
> > + required:
> > + - trip
> > + - cooling-device
>
> 'additionalProperties: false'?
Added
Thanks for the review.
>
> > +
> > +examples:
> > + - |
> > + #include <dt-bindings/interrupt-controller/arm-gic.h>
> > + #include <dt-bindings/thermal/thermal.h>
> > +
> > + // Example 1: SDM845 TSENS
> > + soc: soc@0 {
> > + #address-cells = <2>;
> > + #size-cells = <2>;
> > +
> > + /* ... */
> > +
> > + tsens0: thermal-sensor@...3000 {
> > + compatible = "qcom,sdm845-tsens", "qcom,tsens-v2";
> > + reg = <0 0x0c263000 0 0x1ff>, /* TM */
> > + <0 0x0c222000 0 0x1ff>; /* SROT */
> > + #qcom,sensors = <13>;
> > + interrupts = <GIC_SPI 506 IRQ_TYPE_LEVEL_HIGH>;
> > + interrupt-names = "uplow";
> > + #thermal-sensor-cells = <1>;
> > + };
> > +
> > + tsens1: thermal-sensor@...5000 {
> > + compatible = "qcom,sdm845-tsens", "qcom,tsens-v2";
> > + reg = <0 0x0c265000 0 0x1ff>, /* TM */
> > + <0 0x0c223000 0 0x1ff>; /* SROT */
> > + #qcom,sensors = <8>;
> > + interrupts = <GIC_SPI 507 IRQ_TYPE_LEVEL_HIGH>;
> > + interrupt-names = "uplow";
> > + #thermal-sensor-cells = <1>;
> > + };
> > + };
> > +
> > + /* ... */
> > +
> > + thermal-zones {
> > + cpu0-thermal {
> > + polling-delay-passive = <250>;
> > + polling-delay = <1000>;
> > +
> > + thermal-sensors = <&tsens0 1>;
> > +
> > + trips {
> > + cpu0_alert0: trip-point0 {
> > + temperature = <90000>;
> > + hysteresis = <2000>;
> > + type = "passive";
> > + };
> > +
> > + cpu0_alert1: trip-point1 {
> > + temperature = <95000>;
> > + hysteresis = <2000>;
> > + type = "passive";
> > + };
> > +
> > + cpu0_crit: cpu_crit {
> > + temperature = <110000>;
> > + hysteresis = <1000>;
> > + type = "critical";
> > + };
> > + };
> > +
> > + cooling-maps {
> > + map0 {
> > + trip = <&cpu0_alert0>;
> > + cooling-device = <&CPU0 THERMAL_NO_LIMIT
> > + THERMAL_NO_LIMIT>,
> > + <&CPU1 THERMAL_NO_LIMIT
> > + THERMAL_NO_LIMIT>,
> > + <&CPU2 THERMAL_NO_LIMIT
> > + THERMAL_NO_LIMIT>,
> > + <&CPU3 THERMAL_NO_LIMIT
> > + THERMAL_NO_LIMIT>;
> > + };
> > +
> > + map1 {
> > + trip = <&cpu0_alert1>;
> > + cooling-device = <&CPU0 THERMAL_NO_LIMIT
> > + THERMAL_NO_LIMIT>,
> > + <&CPU1 THERMAL_NO_LIMIT
> > + THERMAL_NO_LIMIT>,
> > + <&CPU2 THERMAL_NO_LIMIT
> > + THERMAL_NO_LIMIT>,
> > + <&CPU3 THERMAL_NO_LIMIT
> > + THERMAL_NO_LIMIT>;
> > + };
> > + };
> > + };
> > +
> > + /* ... */
> > +
> > + cluster0-thermal {
> > + polling-delay-passive = <250>;
> > + polling-delay = <1000>;
> > +
> > + thermal-sensors = <&tsens0 5>;
> > +
> > + trips {
> > + cluster0_alert0: trip-point0 {
> > + temperature = <90000>;
> > + hysteresis = <2000>;
> > + type = "hot";
> > + };
> > + cluster0_crit: cluster0_crit {
> > + temperature = <110000>;
> > + hysteresis = <2000>;
> > + type = "critical";
> > + };
> > + };
> > + };
> > +
> > + /* ... */
> > +
> > + gpu-thermal-top {
> > + polling-delay-passive = <250>;
> > + polling-delay = <1000>;
> > +
> > + thermal-sensors = <&tsens0 11>;
> > +
> > + trips {
> > + gpu1_alert0: trip-point0 {
> > + temperature = <90000>;
> > + hysteresis = <2000>;
> > + type = "hot";
> > + };
> > + };
> > + };
> > + };
> > +...
> > --
> > 2.20.1
> >
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