linux-kernel - Re: [RFC PATCH v3 2/9] power: supply: add cap2ocv batinfo helper

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Message-ID: <8cd66743-242f-f4dd-c767-1f37551c7e78@fi.rohmeurope.com>
Date:   Thu, 18 Nov 2021 05:30:51 +0000
From:   "Vaittinen, Matti" <Matti.Vaittinen@...rohmeurope.com>
To:     Linus Walleij <linus.walleij@...aro.org>
CC:     Matti Vaittinen <mazziesaccount@...il.com>,
        Sebastian Reichel <sre@...nel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Lee Jones <lee.jones@...aro.org>,
        "rostokus@...il.com" <rostokus@...il.com>,
        "fan.chen@...iatek.com" <fan.chen@...iatek.com>,
        "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        linux-power <linux-power@...rohmeurope.com>
Subject: Re: [RFC PATCH v3 2/9] power: supply: add cap2ocv batinfo helper

On 11/18/21 04:02, Linus Walleij wrote:
> On Tue, Nov 16, 2021 at 1:25 PM Matti Vaittinen
> <matti.vaittinen@...rohmeurope.com> wrote:
> 
>> The power-supply core supports concept of OCV (Open Circuit Voltage) =>
>> SOC (State Of Charge) conversion tables. Usually these tables are used
>> to estimate SOC based on OCV. Some systems use so called "Zero Adjust"
>> where at the near end-of-battery condition the SOC from coulomb counter
>> is used to retrieve the OCV - and OCV and VSYS difference is used to
>> re-estimate the battery capacity.
>>
>> Add helper to do look-up the other-way around and also get the OCV
>> based on SOC
>>
>> Signed-off-by: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
> 
> It seems you will need this for your chargers indeed.
> 
>> +int power_supply_dcap2ocv_simple(struct power_supply_battery_ocv_table *table,
>> +                               int table_len, int dcap)
>> +{
>> +       int i, ocv, tmp;
>> +
>> +       for (i = 0; i < table_len; i++)
>> +               if (dcap > table[i].capacity * 10)
>> +                       break;
>> +
>> +       if (i > 0 && i < table_len) {
>> +               tmp = (table[i - 1].ocv - table[i].ocv) *
>> +                     (dcap - table[i].capacity * 10);
>> +
>> +               tmp /= (table[i - 1].capacity - table[i].capacity) * 10;
>> +               ocv = tmp + table[i].ocv;
>> +       } else if (i == 0) {
>> +               ocv = table[0].ocv;
>> +       } else {
>> +               ocv = table[table_len - 1].ocv;
>> +       }
>> +
>> +       return ocv;
>> +}
>> +EXPORT_SYMBOL_GPL(power_supply_dcap2ocv_simple);
> 
> Rewrite this using the library fixpoint interpolation function but just
> copypasting from my patch:
> https://lore.kernel.org/linux-pm/20211116230233.2167104-1-linus.walleij@linaro.org/

Thanks :)
I actually saw this (yesterday?) but didn't revise my patches. Thanks 
for the head's up - it's always good to have this kind of helpers :)

> 
> Other than that it looks good to me!

Thanks!

Best Regards
     --Matti


-- 
The Linux Kernel guy at ROHM Semiconductors

Matti Vaittinen, Linux device drivers
ROHM Semiconductors, Finland SWDC
Kiviharjunlenkki 1E
90220 OULU
FINLAND

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