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 AA111C54FD0 for ; Wed, 25 Mar 2020 10:21:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8CE992078D for ; Wed, 25 Mar 2020 10:21:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727504AbgCYKVT (ORCPT ); Wed, 25 Mar 2020 06:21:19 -0400 Received: from foss.arm.com ([217.140.110.172]:46010 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727450AbgCYKVT (ORCPT ); Wed, 25 Mar 2020 06:21:19 -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 A925631B; Wed, 25 Mar 2020 03:21:18 -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 4CE563F52E; Wed, 25 Mar 2020 03:21:16 -0700 (PDT) Subject: Re: [PATCH v3 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: linux-pm@vger.kernel.org, devicetree@vger.kernel.org References: <1ee4240e29edefc36b5d410d4792971c2bb4c5d5.1585117436.git.amit.kucheria@linaro.org> From: Lukasz Luba Message-ID: Date: Wed, 25 Mar 2020 10:21:14 +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: <1ee4240e29edefc36b5d410d4792971c2bb4c5d5.1585117436.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 Hi Amit, 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 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 > levels (e.g. fans) will contain this property. > > Signed-off-by: Amit Kucheria > --- > .../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 000000000000..b5599f7859f8 > --- /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 > + - 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. [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"; > + }; > + }; > + > + cooling-maps { > + map0 { > + trip = <&cpu0_alert0>; > + cooling-device = <&CPU0 THERMAL_NO_LIMIT > + THERMAL_NO_LIMIT>; Maybe add something like this, to better reflect the description: trip = <&cpu0_alert0>; /* Corresponds to 1000MHz in OPP table */ cooling-device = <&CPU0 5 5>; This is less confusing than THERMAL_NO_LIMIT. Regards, Lukasz