From: Linus Walleij <linus.walleij@linaro.org>
To: Baolin Wang <baolin.wang@linaro.org>
Cc: Sebastian Reichel <sre@kernel.org>,
Rob Herring <robh+dt@kernel.org>,
Mark Rutland <mark.rutland@arm.com>,
Linux PM list <linux-pm@vger.kernel.org>,
"open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE BINDINGS"
<devicetree@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
yuanjiang.yu@unisoc.com, Mark Brown <broonie@kernel.org>,
Craig Tatlor <ctatlor97@gmail.com>
Subject: Re: [PATCH v2 4/4] power: supply: Add Spreadtrum SC27XX fuel gauge unit driver
Date: Wed, 26 Sep 2018 10:09:20 +0200 [thread overview]
Message-ID: <CACRpkdYxV1OBrr6e29OTzE5QCTgt+-2yJGEuYtNM_Mw=41PSyg@mail.gmail.com> (raw)
In-Reply-To: <707ebff8a188d41de374314414c8bfd927183d33.1537930252.git.baolin.wang@linaro.org>
On Wed, Sep 26, 2018 at 5:00 AM Baolin Wang <baolin.wang@linaro.org> 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@unisoc.com>
> Signed-off-by: Baolin Wang <baolin.wang@linaro.org>
> ---
> 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@linaro.org>
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
next prev parent reply other threads:[~2018-09-26 8:09 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-26 2:59 [PATCH v2 1/4] power: supply: core: Introduce one property to present the battery internal resistance Baolin Wang
2018-09-26 2:59 ` [PATCH v2 2/4] power: supply: core: Introduce properties to present the battery OCV table Baolin Wang
2018-09-26 8:02 ` Linus Walleij
2018-09-26 13:51 ` Sebastian Reichel
2018-09-27 1:10 ` Baolin Wang
2018-09-27 6:40 ` Sebastian Reichel
2018-09-26 2:59 ` [PATCH v2 3/4] dt-bindings: power: Add Spreadtrum SC27XX fuel gauge unit documentation Baolin Wang
2018-09-26 8:04 ` Linus Walleij
2018-09-26 14:14 ` Sebastian Reichel
2018-09-26 2:59 ` [PATCH v2 4/4] power: supply: Add Spreadtrum SC27XX fuel gauge unit driver Baolin Wang
2018-09-26 8:09 ` Linus Walleij [this message]
2018-09-26 8:33 ` Baolin Wang
2018-09-26 15:30 ` Sebastian Reichel
2018-09-27 5:17 ` Baolin Wang
2018-09-26 8:00 ` [PATCH v2 1/4] power: supply: core: Introduce one property to present the battery internal resistance Linus Walleij
2018-09-26 8:30 ` Baolin Wang
2018-09-26 12:45 ` Sebastian Reichel
2018-09-27 1:06 ` Baolin Wang
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