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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 17A72C47089 for ; Thu, 27 May 2021 07:13:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EB78861132 for ; Thu, 27 May 2021 07:13:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234808AbhE0HOu (ORCPT ); Thu, 27 May 2021 03:14:50 -0400 Received: from foss.arm.com ([217.140.110.172]:53154 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234709AbhE0HOp (ORCPT ); Thu, 27 May 2021 03:14:45 -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 1445A11D4; Thu, 27 May 2021 00:13:13 -0700 (PDT) Received: from [10.57.31.236] (unknown [10.57.31.236]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 011343F73B; Thu, 27 May 2021 00:13:10 -0700 (PDT) Subject: Re: [PATCH v2 0/3] EM / PM: Inefficient OPPs To: Viresh Kumar Cc: Vincent Donnefort , peterz@infradead.org, rjw@rjwysocki.net, vincent.guittot@linaro.org, qperret@google.com, linux-kernel@vger.kernel.org, ionela.voinescu@arm.com, dietmar.eggemann@arm.com References: <1621616064-340235-1-git-send-email-vincent.donnefort@arm.com> <20210526034751.5fl4kekq73gqy2wq@vireshk-i7> <068fa9c4-2b55-3d75-adc7-cf5ef2174b12@arm.com> <20210526093318.cbtjkybzwdchxi5y@vireshk-i7> From: Lukasz Luba Message-ID: Date: Thu, 27 May 2021 08:13:09 +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: <20210526093318.cbtjkybzwdchxi5y@vireshk-i7> 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-kernel@vger.kernel.org Hi Viresh, On 5/26/21 10:33 AM, Viresh Kumar wrote: > On 26-05-21, 09:56, Lukasz Luba wrote: >> No, these OPPs have to stay because they are used in thermal for cooling >> states. > > This won't break the thermal tables. Thermal just sets the max-freq for a CPU, > and it doesn't depend on the OPP table for that. > >> DT cooling devices might have them set as a scope of possible >> states. We don't want to break existing platforms, don't we? > > I don't think we will end up breaking anything here. > >> We want to 'avoid' those OPPs when possible (no thermal pressure), but >> we might have to use them sometimes. > > Why would we want to use them if they are inefficient ? Thermal or something > else as well ? > > More in the other reply I am sending to Vincent. > I have responded to your email there. I don't know if you have seen it. As I said there, these OPPs, which from energy perspective we call 'inefficient', might be used to provide enough performance under thermal constraints. Regards, Lukasz