On Wed, Sep 26, 2018 at 5:00 AM Baolin Wang <baolin.wang@xxxxxxxxxx> wrote: > This patch adds the Spreadtrum SC27XX serial PMICs fuel gauge support, > which is used to calculate the battery capacity. > > Original-by: Yuanjiang Yu <yuanjiang.yu@xxxxxxxxxx> > Signed-off-by: Baolin Wang <baolin.wang@xxxxxxxxxx> > --- > Changes from v1: > - Use battery standard properties to get internal resistance and ocv table. > - Change devm_gpiod_get_optional() to devm_gpiod_get(). > - Add power_supply_changed() when detecting battery present change. > - Return micro volts for sc27xx_fgu_get_vbat_ocv(). Acked-by: Linus Walleij <linus.walleij@xxxxxxxxxx> I see that you need to have the internal resistance as parameter to this equation so it needs to come in. (I guess as factor/typical internal resistance as suggested.) IIUC this reliance on an uncertain internal resistance is the reason why fuel gauges / coloumb counters are seen as crude ways to estimate battery capacity, and their accuracy and reliability worsen over the lifetime of the battery, and this is why safety-critical devices include ways to measure the internal resistance as well. But the hardware is as it is, and probably for some good reasons, like cost. Yours, Linus Walleij
