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=-8.5 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 2AFECC4727F for ; Wed, 30 Sep 2020 08:25:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E5D312076E for ; Wed, 30 Sep 2020 08:25:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728346AbgI3IZ0 (ORCPT ); Wed, 30 Sep 2020 04:25:26 -0400 Received: from foss.arm.com ([217.140.110.172]:59372 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728563AbgI3IZZ (ORCPT ); Wed, 30 Sep 2020 04:25:25 -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 456A2D6E; Wed, 30 Sep 2020 01:25:25 -0700 (PDT) Received: from [10.57.54.5] (unknown [10.57.54.5]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id D99613F6CF; Wed, 30 Sep 2020 01:25:22 -0700 (PDT) Subject: Re: [PATCH 1/2] docs: Clarify abstract scale usage for power values in Energy Model To: Doug Anderson Cc: LKML , Linux PM , linux-doc@vger.kernel.org, Jonathan Corbet , Daniel Lezcano , Dietmar.Eggemann@arm.com, Quentin Perret , Matthias Kaehlcke , "Rafael J. Wysocki" , Rajendra Nayak References: <20200929121610.16060-1-lukasz.luba@arm.com> From: Lukasz Luba Message-ID: Date: Wed, 30 Sep 2020 09:25:21 +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 Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Hi Douglas, On 9/30/20 12:53 AM, Doug Anderson wrote: > Hi, > > On Tue, Sep 29, 2020 at 5:16 AM Lukasz Luba wrote: >> >> The Energy Model (EM) can store power values in milli-Watts or in abstract >> scale. This might cause issues in the subsystems which use the EM for >> estimating the device power, such as: >> - mixing of different scales in a subsystem which uses multiple >> (cooling) devices (e.g. thermal Intelligent Power Allocation (IPA)) >> - assuming that energy [milli-Joules] can be derived from the EM power >> values which might not be possible since the power scale doesn't have to >> be in milli-Watts >> >> To avoid misconfiguration add the needed documentation to the EM and >> related subsystems: EAS and IPA. >> >> Signed-off-by: Lukasz Luba >> --- >> .../driver-api/thermal/power_allocator.rst | 8 ++++++++ >> Documentation/power/energy-model.rst | 13 +++++++++++++ >> Documentation/scheduler/sched-energy.rst | 5 +++++ >> 3 files changed, 26 insertions(+) > > I haven't read through these files in massive detail, but the quick > skim makes me believe that your additions seem sane. In general, I'm > happy with documenting reality, thus: > > Reviewed-by: Douglas Anderson Thank you for the review. > > I will note: you haven't actually updated the device tree bindings. > Thus, presumably, anyone who is specifying these numbers in the device > tree is still supposed to specify them in a way that mW can be > recovered, right? Said another way: nothing about your patches makes > it OK to specify numbers in device trees using an "abstract scale", > right? For completeness, we are talking here about the binding from: Documentation/devicetree/bindings/arm/cpus.yaml which is 'dynamic-power-coefficient'. Yes, it stays untouched, also the unit (uW/MHz/V^2) which then allows to have mW in the power values in the EM. Regards, Lukasz