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 E998CC10F26 for ; Wed, 1 Apr 2020 12:34:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C9C3A20714 for ; Wed, 1 Apr 2020 12:34:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732398AbgDAMep (ORCPT ); Wed, 1 Apr 2020 08:34:45 -0400 Received: from foss.arm.com ([217.140.110.172]:50672 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726974AbgDAMeo (ORCPT ); Wed, 1 Apr 2020 08:34:44 -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 128C130E; Wed, 1 Apr 2020 05:34:44 -0700 (PDT) Received: from [10.37.12.63] (unknown [10.37.12.63]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 89A7A3F68F; Wed, 1 Apr 2020 05:34:41 -0700 (PDT) Subject: Re: [PATCH v4 2/3] dt-bindings: thermal: Add yaml bindings for thermal cooling-devices 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: Rob Herring , linux-pm@vger.kernel.org, devicetree@vger.kernel.org References: From: Lukasz Luba Message-ID: <44bef00a-ffd1-4154-1b8c-77aae9ccc20d@arm.com> Date: Wed, 1 Apr 2020 13:34:39 +0100 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: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/1/20 12:15 PM, 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 property #cooling-cells is required in each device that acts as a > cooling device - whether active or passive. So any device that can > throttle its performance to passively reduce heat dissipation (e.g. > cpus, gpus) and any device that can actively dissipate heat at different maybe CPUs, GPUs > levels (e.g. fans) will contain this property. > > Signed-off-by: Amit Kucheria > Reviewed-by: Rob Herring > --- > Changes since v3: > - Clarify example by using cooling state numbers and a comment > > .../thermal/thermal-cooling-devices.yaml | 116 ++++++++++++++++++ > 1 file changed, 116 insertions(+) > create mode 100644 Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml > > diff --git a/Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml b/Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml > new file mode 100644 > index 0000000000000..0dc4a743a1351 > --- /dev/null > +++ b/Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml > @@ -0,0 +1,116 @@ > +# SPDX-License-Identifier: (GPL-2.0) > +# Copyright 2020 Linaro Ltd. > +%YAML 1.2 > +--- > +$id: http://devicetree.org/schemas/thermal/thermal-cooling-devices.yaml# > +$schema: http://devicetree.org/meta-schemas/core.yaml# > + > +title: Thermal cooling device 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 overload. > + > + 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 s/artively/actively > + - thermal-zones: a container of the following node types used to describe all > + thermal data for the platform > + > + This binding describes the cooling devices. > + > + There are essentially two ways to provide control on power dissipation: > + - Passive cooling: by means of regulating device performance. A typical > + passive cooling mechanism is a CPU that has dynamic voltage and frequency > + scaling (DVFS), and uses lower frequencies as cooling states. > + - Active cooling: by means of activating devices in order to remove the > + dissipated heat, e.g. regulating fan speeds. > + > + Any cooling device has a range of cooling states (i.e. different levels of > + heat dissipation). They also have a way to determine the state of cooling in > + which the device is. For example, a fan's cooling states correspond to the > + different fan speeds possible. Cooling states are referred to by single > + unsigned integers, where larger numbers mean greater heat dissipation. The > + precise set of cooling states associated with a device should be defined in > + a particular device's binding. > + > +select: true > + > +properties: > + "#cooling-cells": > + description: > + Must be 2, in order to specify minimum and maximum cooling state used in > + the cooling-maps reference. The first cell is the minimum cooling state > + and the second cell is the maximum cooling state requested. > + const: 2 > + > +examples: > + - | > + #include > + #include > + > + // Example 1: Cpufreq cooling device on CPU0 > + cpus { > + #address-cells = <2>; > + #size-cells = <0>; > + > + CPU0: cpu@0 { > + device_type = "cpu"; > + compatible = "qcom,kryo385"; > + reg = <0x0 0x0>; > + enable-method = "psci"; > + cpu-idle-states = <&LITTLE_CPU_SLEEP_0 > + &LITTLE_CPU_SLEEP_1 > + &CLUSTER_SLEEP_0>; > + capacity-dmips-mhz = <607>; > + dynamic-power-coefficient = <100>; > + qcom,freq-domain = <&cpufreq_hw 0>; > + #cooling-cells = <2>; > + next-level-cache = <&L2_0>; > + L2_0: l2-cache { > + compatible = "cache"; > + next-level-cache = <&L3_0>; > + L3_0: l3-cache { > + compatible = "cache"; > + }; > + }; > + }; > + > + /* ... */ > + > + }; > + > + /* ... */ > + > + 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"; > + }; > + }; > + > + cooling-maps { > + map0 { > + trip = <&cpu0_alert0>; > + /* Corresponds to 1000MHz in OPP table */ > + cooling-device = <&CPU0 5 5>; > + }; > + }; > + }; > + > + /* ... */ > + }; > +... > Apart from that, looks good: Reviewed-by: Lukasz Luba Regards, Lukasz