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[2001:14ba:16ee:fa00::4]) by smtp.gmail.com with ESMTPSA id n7sm495101lfu.116.2021.11.26.04.35.19 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 26 Nov 2021 04:35:20 -0800 (PST) Message-ID: <28df4678-345b-78e0-06f0-1fdcbaff455d@gmail.com> Date: Fri, 26 Nov 2021 14:35:18 +0200 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.1.0 Content-Language: en-US To: "Vaittinen, Matti" , Linus Walleij Cc: 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 , "Mutanen, Mikko" 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> From: Matti Vaittinen Subject: Re: [RFC PATCH v3 3/9] power: supply: Support DT originated temperature-capacity tables In-Reply-To: <676253b9-ff69-7891-1f26-a8b5bb5a421b@fi.rohmeurope.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 11/26/21 13:56, Vaittinen, Matti wrote: > Hi dee Ho again, > > On 11/18/21 08:11, Matti Vaittinen wrote: >> Hi Linus, >> >> On 11/18/21 04:10, Linus Walleij wrote: >>> On Tue, Nov 16, 2021 at 1:26 PM Matti Vaittinen >>> wrote: >>> >>>> Support obtaining the "capacity degradation by temperature" - tables >>>> from device-tree to batinfo. >>>> >>>> Signed-off-by: Matti Vaittinen >>> >>> Same questions as on the binding patch. >>> >>> If we already support different degradation by temperature tables, >>> why do we need a second mechanism for the same thing? >> >> Thanks for bringing this up. As I said, I didn't notice that we could >> indeed use the CAP-OCV tables for different temperatures to bring in >> this information :) I see certain benefit from the possibility of not >> requiring to measure the OCV at different temperatures - but it may not >> be meaningful. As I replied to your patch 1/9 review - I need to (try >> to) do some more research... > > > I don't see providing OCV tables at different temperature gives the > degradation of battery capacity. Whoah. A big thought for Friday. > > We get the OCV => SOC correspondance at different temperatures. I > however don't see how this gives the OCV => energy relation. After reading what I wrote even I didn't know what I tried to say. Well, I think I tried to explain that I don't see how we can use this information to do any estimation what the Coulomb Counter reading represent at the given temperature. This is what the temperature-degradation tables aim to give us. As far as I > know both the OCV and the 'amount of uAhs battery is able to store' are > impacted by temperature change. This means, seeing the OCV => SOC at > different temperatures does not tell us what is the impact of > temperature to the OCV, and what is the impact to SOC. I think I tried to say that these curves don't help us to tell how many uAhs we have in battery with different temperatures when battery is empty, or half full or, ... Again, what we would like to know is what SOC our CC value represents - and use OCV to just adjust this further (or in some cases to correct the CC value using OCV - if we can trust the battery to be properly relaxed). Hope this did clarify. Afraid it didn't :) Best Regards -- Matti Vaittinen