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=-5.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,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 3C736C433E7 for ; Wed, 2 Sep 2020 05:36:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 13538206C0 for ; Wed, 2 Sep 2020 05:36:29 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=mg.codeaurora.org header.i=@mg.codeaurora.org header.b="EiaDVic3" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726285AbgIBFgZ (ORCPT ); Wed, 2 Sep 2020 01:36:25 -0400 Received: from mail29.static.mailgun.info ([104.130.122.29]:19914 "EHLO mail29.static.mailgun.info" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725774AbgIBFgY (ORCPT ); Wed, 2 Sep 2020 01:36:24 -0400 DKIM-Signature: a=rsa-sha256; v=1; c=relaxed/relaxed; d=mg.codeaurora.org; q=dns/txt; s=smtp; t=1599024984; h=Content-Transfer-Encoding: Content-Type: In-Reply-To: MIME-Version: Date: Message-ID: From: References: Cc: To: Subject: Sender; bh=Ji73SYobjua5kOTQythFn0xAJRkAQsD505nfnZi/Ywk=; b=EiaDVic3f40znoT9uB4LuFaRlfR/VcPpaiP5VRPS6LwmwYZ9cnUnJQyH3X555Ut2Y9vrWVDs Iu6Wsh/Q6MZXnzaWEybkLk37vP9WQTBm+f15BTKpKm1fyXPwLvTJ/y+qPAf1CSmC4zWvF3j7 OoGCIimJ0+jfm2PyLp4Hm2L1azc= X-Mailgun-Sending-Ip: 104.130.122.29 X-Mailgun-Sid: WyI1YmJiNiIsICJkZXZpY2V0cmVlQHZnZXIua2VybmVsLm9yZyIsICJiZTllNGEiXQ== Received: from smtp.codeaurora.org (ec2-35-166-182-171.us-west-2.compute.amazonaws.com [35.166.182.171]) by smtp-out-n05.prod.us-west-2.postgun.com with SMTP id 5f4f2f4cd7b4e26913b82f51 (version=TLS1.2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256); Wed, 02 Sep 2020 05:36:12 GMT Received: by smtp.codeaurora.org (Postfix, from userid 1001) id 83463C43391; Wed, 2 Sep 2020 05:36:12 +0000 (UTC) Received: from [192.168.1.16] (unknown [61.1.229.146]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: rnayak) by smtp.codeaurora.org (Postfix) with ESMTPSA id EFBFBC433C6; Wed, 2 Sep 2020 05:36:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org EFBFBC433C6 Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: aws-us-west-2-caf-mail-1.web.codeaurora.org; spf=none smtp.mailfrom=rnayak@codeaurora.org Subject: Re: [PATCH] arm64: dts: qcom: sc7180: Add 'sustainable_power' for CPU thermal zones To: Doug Anderson , Matthias Kaehlcke Cc: Andy Gross , Bjorn Andersson , Rob Herring , Mark Rutland , "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS" , linux-arm-msm , LKML , Amit Kucheria , Sai Prakash Ranjan References: <20200813113030.1.I89c33c4119eaffb986b1e8c1bc6f0e30267089cd@changeid> <20200901170745.GA3419728@google.com> From: Rajendra Nayak Message-ID: <8ad0589e-102d-7523-899f-0ebe85b7d2b8@codeaurora.org> Date: Wed, 2 Sep 2020 11:06:06 +0530 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 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: devicetree-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org > * In terms of the numbers here, I believe that you're claiming that we > can dissipate 768 mW * 6 + 1202 mW * 2 = ~7 Watts of power. My memory > of how much power we could dissipate in previous laptops I worked on > is a little fuzzy, but that doesn't seem insane for a passively-cooled > laptop. However, I think someone could conceivably put this chip in a > smaller form factor. In such a case, it seems like we'd want these > things to sum up to ~2000 (if it would ever make sense for someone to > put this chip in a phone) or ~4000 (if it would ever make sense for > someone to put this chip in a small tablet). It seems possible that, > to achieve this, we might have to tweak the > "dynamic-power-coefficient". DPC values are calculated (at a SoC) by actually measuring max power at various frequency/voltage combinations by running things like dhrystone. How would the max power a SoC can generate depend on form factors? How much it can dissipate sure is, but then I am not super familiar how thermal frameworks end up using DPC for calculating power dissipated, I am guessing they don't. > I don't know how much thought was put > into those numbers, but the fact that the little cores have a super > round 100 for their dynamic-power-coefficient makes me feel like they > might have been more schwags than anything. Rajendra maybe knows? FWIK, the values are always scaled and normalized to 100 for silver and then used to derive the relative DPC number for gold. If you see the DPC for silver cores even on sdm845 is a 100. Again these are not estimations but based on actual power measurements. -- QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation