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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id CED2AC433FE for ; Sun, 5 Dec 2021 00:30:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230078AbhLEAdt (ORCPT ); Sat, 4 Dec 2021 19:33:49 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:52478 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229772AbhLEAds (ORCPT ); Sat, 4 Dec 2021 19:33:48 -0500 Received: from mail-ot1-x334.google.com (mail-ot1-x334.google.com [IPv6:2607:f8b0:4864:20::334]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9F214C061751 for ; Sat, 4 Dec 2021 16:30:22 -0800 (PST) Received: by mail-ot1-x334.google.com with SMTP id a23-20020a9d4717000000b0056c15d6d0caso8583141otf.12 for ; Sat, 04 Dec 2021 16:30:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=6y71zrGyUm53y6etkENkH9vk53uSF1GEIKxh02HrJ44=; b=yN5cu+ds8GQINJ5qZy5fjmyWkWQVxzZg2Q5Is9ekfb+VTtXPDu2MrvFT5SgLathLDb Frex9UuWeygJNnL3xsAZu1F0NzhApY6g3eEK0KhjldnOi1vSAVFpNCs4Fai1H5xOhoHz 3WPhAXqeUeJJA7gFlJ/hq1aPa8ZrmuECvlMUfhMdiG9RNop260MHGUVwNiBmmC17QzXo X+35GyKBrePRmitKCV23+dD+bDsb2lR2PbZs8GNfgz5yiCMzIRIVpy65eFQb1A/w+Vh9 Bc92eSgLRLRtWUmLMPS50dZXhXAJcxKgRuLrJCzOD3gC630rt2S7zT9nqZGAExiZiY2B Swjw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=6y71zrGyUm53y6etkENkH9vk53uSF1GEIKxh02HrJ44=; b=4uuDgXtWO/+yAlwfofzu76eZx4kM8JGSDgOp3Im24aUjlVvOF23yKYsjuQ9u40hth2 D1UiF/tLWgO1BJGpoUxN/xH8g17wxBPD4hpWGJDlwBWiKjywU4V+RRrkOUbZ5G1i7VXT lvXcbob8JijFKuPtjPiHg2CxBxvz0YBvqjIcHHWy76770sdM1wnvrvvMrC3YbHfvQ9j3 yv7jGp5fnllLDiir88qwDK9niYcM42sqJzGnpS89xagxJKccsEUGds2ZmoCuTo6a3Wi5 ODYQTaoAbgMyxwDSQfVUmz0KpwWnWMuZa0hn7Jt0QTyNs+8rHOY2XD6dTnQo7a5RJyeZ SOew== X-Gm-Message-State: AOAM533ZaJCrA+0v6esjbHV+T/YT5Pa4e1+cxCSHiRl5thjD0EogkCHV msqjMxz+FffYZyrq/y3omIEyaw/RNqyPBo2lkBkZ0g== X-Google-Smtp-Source: ABdhPJwkGm2r7mHDrjNl3YQJbeXL52IHT7NtrtzaW/i6kh0H/ZxP82a0eia2lqUU9Gm25ADttUCPF+N1M9UL1kKteio= X-Received: by 2002:a9d:ed6:: with SMTP id 80mr22880693otj.35.1638664221225; Sat, 04 Dec 2021 16:30:21 -0800 (PST) MIME-Version: 1.0 References: <6123f62ac44e6513a498d15034a4b6b22abe5f5b.1637061794.git.matti.vaittinen@fi.rohmeurope.com> <7b34e88f-54f3-6d0a-293e-b2b411d1c5c2@fi.rohmeurope.com> <676253b9-ff69-7891-1f26-a8b5bb5a421b@fi.rohmeurope.com> <57f97c5f-aedb-7f7e-d269-90bd97bbba09@fi.rohmeurope.com> <78f44e65-e788-22a0-5141-fb86f08c5522@fi.rohmeurope.com> In-Reply-To: <78f44e65-e788-22a0-5141-fb86f08c5522@fi.rohmeurope.com> From: Linus Walleij Date: Sun, 5 Dec 2021 01:30:09 +0100 Message-ID: Subject: Re: [RFC PATCH v3 3/9] power: supply: Support DT originated temperature-capacity tables To: "Vaittinen, Matti" Cc: Matti Vaittinen , Sebastian Reichel , Rob Herring , Lee Jones , "rostokus@gmail.com" , "fan.chen@mediatek.com" , "linux-pm@vger.kernel.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , linux-power , =?UTF-8?B?c2hpbWkgPj4g5riF5rC0IOW0h+W8mA==?= Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Matti, On Thu, Dec 2, 2021 at 7:29 AM Vaittinen, Matti wrote: (fast forward the stuff where we are in violent agreement) > What I was now considering is that maybe the capacity drop (in uAhs) > caused by the temperature change - is not the same for new and old > battery. It sounds more logical to me that the capacity drop caused by > the temperature is proportional to the maximum capacity battery is > having at that point of it's life. Eg, if new battery can hold 80 units > of energy, and drops 20 units of energy when temperature changes from T0 > => T1 - an badly aged battery which now only can hold 40 units would > lose only 10 units at that same temperature drop T0 => T1. I was > wondering if such an assumption is closer to the truth than saying that > bot of the batteries would lose same 20 units - meaning that the new > battery would lose 25% of energy at temperature drop T0 => T1 but old > one would lose 50% of the capacity. I somehow think both of the > batteries, old and new, would lose same % of capacity at the temperature > change. > > So, if this assumption is correct, then we should give the temperature > impact as proportion of the full capacity taking the aging into account. This looks plausible. > My problem here is that I just assume the impact of temperature is > proportional to the full-capacity which takes the aging into account. > Knowing how this really is would be cool so we could get the temperature > impact modelled correctly in DT. I suppose we should check some IEEE articles to verify that this is the case before assuming. I have access to them but no time to read :( > > Yes there is some tight community of electronic engineers who read the > > right articles and design these things. We don't know them :( > > Right. By the way, I heard tha the TI has patent protecting some type of > battery internal resistance usage here. OTOH, ROHM has patent over some > of the VDROP value table stuff. Occasionally it feels like the ice is > getting thinner at each step here. :/ This is none of our concern. Patents are concerns for people shipping devices, not for open source code. Also patents are only valid for 20 years and we are looking at longer times anyway. If we define generic DT properties for this they will be used more than 20 years from now. We even have patented code in the kernel, see: Documentation/RCU/rcu.rst Yours, Linus Walleij