Date: Tue, 25 Oct 2016 12:56:04 +0200
From: Pavel Machek <pavel@ucw.cz>
To: Pali =?iso-8859-1?Q?Roh=E1r?= <pali.rohar@gmail.com>
Cc: Tony Lindgren <tony@atomide.com>, sre@kernel.org,
        kernel list <linux-kernel@vger.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
        linux-omap@vger.kernel.org, khilman@kernel.org, aaro.koskinen@iki.fi,
        ivo.g.dimitrov.75@gmail.com, patrikbachan@gmail.com, serge@hallyn.com,
        abcloriens@gmail.com
Subject: Re: [RFC] shutdown machine when li-ion battery goes below 3V
Message-ID: <20161025105604.GA25855@amd>
References: <20161024212250.GA31336@amd>
 <20161024212932.uhjz752z2cy5hohl@atomide.com>
 <20161024214152.GA32310@amd>
 <201610242348.47484@pali>
 <20161025102435.GA6916@amd>
 <20161025105320.GK12154@pali>
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On Tue 2016-10-25 12:53:20, Pali Roh=E1r wrote:
> On Tuesday 25 October 2016 12:24:35 Pavel Machek wrote:
> > On Mon 2016-10-24 23:48:47, Pali Roh=E1r wrote:
> > > On Monday 24 October 2016 23:41:52 Pavel Machek wrote:
> > > > On Mon 2016-10-24 14:29:33, Tony Lindgren wrote:
> > > > > Also, the shutdown voltage can depend on external devices
> > > > > connected. It could be for example 3.3V depending on eMMC on some
> > > > > devices while devices with no eMMC could have it at 3.0V.
> > > >=20
> > > > Actually, I'd like to shutdown at 3.3V or more (like 3.5V), because
> > > > going below that is pretty mean to the battery. But if I set
> > > > threshold too high, GSM activity will push it below that for a very
> > > > short while, and I'll shutdown too soon.
> > > >=20
> > > > Ideas welcome...
> > >=20
> > > bq27x00 has EDVF flag which means that battery is empty. Maemo with=
=20
> > > bq27x00 driver is configured to issue system shutdown when EDVF is se=
t.
> > >=20
> > > Maybe kernel should issue emergency shutdown e.g. after minute or two=
=20
> > > after EDVF flag is set?
> >=20
> > Thanks for pointer.
> >=20
> > EDVF seems to be exposed as health. ... but only if battery is
> > calibrated, AFAICT.
>=20
> No, EDVF is available also for uncalibrated battery. There are EDV1 and
> EDVF flags. Both are set based on battery voltage and some other
> parameters from bq EEPROM.
>=20
> >  if (has_ci_flag && (cache.flags & BQ27000_FLAG_CI)) {
> >       dev_info_once(di->dev, "battery is not calibrated! ignoring capac=
ity values\n");
>=20
> Yes, it ignores only capacity values (which needs calibration), not
> those raw flags which works also without calibration.
>=20
> >       ...
> >       cache.health =3D -ENODATA;

Take a look at code. Health is not read from hardware unless battery
is calibrated.
							=09
								Pavel

--=20
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo=
g.html

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