linux-kernel - Re: [RFC PATCH v3 7/9] power: supply: add simple-gauge for SOC estimation and CC correction

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Date:   Fri, 19 Nov 2021 02:54:09 +0100
From:   Linus Walleij <linus.walleij@...aro.org>
To:     Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
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,
        fan.chen@...iatek.com, linux-pm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-power@...rohmeurope.com
Subject: Re: [RFC PATCH v3 7/9] power: supply: add simple-gauge for SOC
 estimation and CC correction

On Tue, Nov 16, 2021 at 1:28 PM Matti Vaittinen
<matti.vaittinen@...rohmeurope.com> wrote:

> Add generic 'simple gauge' helper for performing iterative SOC estimation
> and coulomb counter correction for devices with a (drifting) coulomb
> counter. This should allow few charger/fuel-gauge drivers to use generic
> loop instead of implementing their own.
>
> Charger/fuel-gauge drivers can register 'simple-gauge' which does
> periodically poll the driver and:
>  - get battery state
>  - adjust coulomb counter value (to fix drifting caused for example by ADC
>    offset) if:
>      - Battery is relaxed and OCV<=>SOC table is given
>      - Battery is full charged
>  - get battery age (cycles) from driver
>  - get battery temperature
>  - do battery capacity correction
>      - by battery temperature
>      - by battery age
>      - by computed Vbat/OCV difference at low-battery condition if
>        low-limit is set and OCV table given
>      - by IC specific low-battery correction if provided
>  - compute current State Of Charge (SOC)
>  - do periodical calibration if IC supports that. (Many ICs do calibration
>    of CC by shorting the ADC pins and getting the offset).
>  - provide the user-space a consistent interface for getting/setting the
>    battery-cycle information for ICs which can't store the battery aging
>    information. Uses POWER_SUPPLY_PROP_CYCLE_COUNT for this.
>
> The simple gauge provides the last computed SOC as
> POWER_SUPPLY_PROP_CAPACITY to power_supply_class when requested.
>
> Things that should/could be added but are missing from this commit:
>  - Support starting calibration in HW when entering to suspend. This
>    is useful for ICs supporting delayed calibration to mitigate CC error
>    during suspend - and to make periodical wake-up less critical.
>  - periodical wake-up for performing SOC estimation computation (RTC
>    integration)
>
> Signed-off-by: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>

This is the right ambition, I haven't looked close at it but the way
you use it seem to be what you need, so:
Acked-by: Linus Walleij <linus.walleij@...aro.org>
(and the rest of the patches to the Rohm chips)

Yours,
Linus Walleij