From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 08BD7C54FD0 for ; Wed, 25 Mar 2020 11:06:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D6B3820714 for ; Wed, 25 Mar 2020 11:06:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727313AbgCYLGc (ORCPT ); Wed, 25 Mar 2020 07:06:32 -0400 Received: from foss.arm.com ([217.140.110.172]:46696 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726842AbgCYLGc (ORCPT ); Wed, 25 Mar 2020 07:06:32 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 1164231B; Wed, 25 Mar 2020 04:06:31 -0700 (PDT) Received: from [10.37.12.110] (unknown [10.37.12.110]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id C30883F71F; Wed, 25 Mar 2020 04:06:28 -0700 (PDT) Subject: Re: [PATCH v3 3/3] dt-bindings: thermal: Add yaml bindings for thermal zones To: Amit Kucheria , linux-kernel@vger.kernel.org, linux-arm-msm@vger.kernel.org, swboyd@chromium.org, mka@chromium.org, daniel.lezcano@linaro.org, Amit Kucheria , Zhang Rui Cc: linux-pm@vger.kernel.org, devicetree@vger.kernel.org References: <9c447186008ef2e3f4c3e712458dc0ddcd8a8b03.1585117436.git.amit.kucheria@linaro.org> From: Lukasz Luba Message-ID: <81b0cbe1-23c8-b4a3-4775-62e7d6c49b6b@arm.com> Date: Wed, 25 Mar 2020 11:06:27 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <9c447186008ef2e3f4c3e712458dc0ddcd8a8b03.1585117436.git.amit.kucheria@linaro.org> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-arm-msm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-arm-msm@vger.kernel.org On 3/25/20 6:34 AM, Amit Kucheria 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 > --- > Changes since v2: > - Addressed review comment from Rob > - Added required properties for thermal-zones node > - Added select: true to thermal-cooling-devices.yaml > - Fixed up example to pass dt_binding_check > > .../bindings/thermal/thermal-zones.yaml | 324 ++++++++++++++++++ > 1 file changed, 324 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..5632304dcf62 > --- /dev/null > +++ b/Documentation/devicetree/bindings/thermal/thermal-zones.yaml > @@ -0,0 +1,324 @@ > +# SPDX-License-Identifier: (GPL-2.0) > +# 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 > + > +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 actively > + - 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: > + $nodename: > + const: thermal-zones > + description: > + A /thermal-zones node is required in order to use the thermal framework to > + manage input from the various thermal zones in the system in order to > + mitigate thermal overload conditions. It does not represent a real device > + in the system, but acts as a container to link thermal sensor devices, I would say 'thermal sensor device', since there is 1-to-1 mapping and aggregating a few sensors inside one tz is not allowed (or I missed some patches queuing). > + platform-data regarding temperature thresholds and the mitigation actions > + to take when the temperature crosses those thresholds. > + > +patternProperties: > + "^[a-zA-Z][a-zA-Z0-9\\-]{1,12}-thermal$": > + 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 > + 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 > + 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: > + $ref: /schemas/types.yaml#/definitions/phandle-array > + description: > + A list of thermal sensor phandles and sensor specifiers used to > + monitor this thermal zone. I don't know why it's not consistent with the actual code in of-thermal.c, where there is even a comment stated: /* For now, thermal framework supports only 1 sensor per zone */ I think this is the place where developers should be informed about the limitation and not even try to put more sensors into the list. > + > + trips: > + type: object > + description: > + This node describes a set of points in the temperature domain at > + which the thermal framework needs to takes action. The actions to s/needs to takes/needs to take/ > + be taken are defined in another node called cooling-maps. > + > + patternProperties: > + "^[a-zA-Z][a-zA-Z0-9\\-_]{0,63}$": > + type: object > + > + properties: > + temperature: > + $ref: /schemas/types.yaml#/definitions/int32 > + minimum: -273000 > + maximum: 200000 > + description: > + An integer expressing the trip temperature in millicelsius. > + > + 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. This property is worth a bit longer description. > + > + type: > + $ref: /schemas/types.yaml#/definitions/string > + enum: > + - active # enable active cooling e.g. fans > + - passive # enable passive cooling e.g. throttling cpu > + - hot # send notification to driver > + - critical # send notification to driver, trigger shutdown > + description: | > + There are four valid trip types: active, passive, hot, > + critical. [snip] > + > + 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>; From this two examples of handling cpu0_alert0 and cpu0_alert1 you cannot conclude anything (if you don't understand thermal framework (and probably IPA). As a simple example it would be better to put a comment with a description and limit min, max to a specific OPP: map0 { trip = <&cpu0_alert0>; /* Corresponds to 1400MHz in OPP table */ cooling-device = <&CPU0 3 3>, <&CPU1 3 3>, <&CPU2 3 3>, <&CPU3 3 3>; }; map1 { trip = <&cpu0_alert1>; /* Corresponds to 1000MHz in OPP table */ cooling-device = <&CPU0 5 5>, <&CPU1 5 5>, <&CPU2 5 5>, <&CPU3 5 5>; }; IMHO this kind of example would tell more to an avg driver developer. Regards, Lukasz