linux-kernel - Re: [PATCH] sbs-battery: fix power status when battery is dry

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Date:	Fri, 25 Mar 2016 11:06:30 +0800
From:	Daniel Kurtz <djkurtz@...omium.org>
To:	YH Huang <yh.huang@...iatek.com>
Cc:	Sebastian Reichel <sre@...nel.org>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	David Woodhouse <dwmw2@...radead.org>,
	Matthias Brugger <matthias.bgg@...il.com>,
	linux-pm@...r.kernel.org,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"moderated list:ARM/Mediatek SoC support" 
	<linux-mediatek@...ts.infradead.org>
Subject: Re: [PATCH] sbs-battery: fix power status when battery is dry

On Thu, Mar 24, 2016 at 2:43 PM, YH Huang <yh.huang@...iatek.com> wrote:
>
> Hi Daniel,
>
> On Thu, 2016-03-24 at 12:01 +0800, Daniel Kurtz wrote:
> > Hi YH,
> >
> > On Wed, Mar 23, 2016 at 5:53 PM, YH Huang <yh.huang@...iatek.com> wrote:
> > > When the battery is dry and BATTERY_FULL_DISCHARGED is set,
> > > we should check BATTERY_DISCHARGING to decide the power status.
> > > If BATTERY_DISCHARGING is set, the power status is not charging.
> > > Or the power status should be charging.
> > >
> > > Signed-off-by: YH Huang <yh.huang@...iatek.com>
> > > ---
> > >  drivers/power/sbs-battery.c |   22 ++++++++++++----------
> > >  1 file changed, 12 insertions(+), 10 deletions(-)
> > >
> > > diff --git a/drivers/power/sbs-battery.c b/drivers/power/sbs-battery.c
> > > index d6226d6..d86db0e 100644
> > > --- a/drivers/power/sbs-battery.c
> > > +++ b/drivers/power/sbs-battery.c
> > > @@ -382,11 +382,12 @@ static int sbs_get_battery_property(struct i2c_client *client,
> > >
> > >                 if (ret & BATTERY_FULL_CHARGED)
> > >                         val->intval = POWER_SUPPLY_STATUS_FULL;
> > > -               else if (ret & BATTERY_FULL_DISCHARGED)
> > > -                       val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
> > > -               else if (ret & BATTERY_DISCHARGING)
> > > -                       val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
> > > -               else
> > > +               else if (ret & BATTERY_DISCHARGING) {
> > > +                       if (ret & BATTERY_FULL_DISCHARGED)
> > > +                               val->intval = POWER_SUPPLY_STATUS_NOT_CHARGING;
> > > +                       else
> > > +                               val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
> > > +               } else
> >
> >
> > I think (BATTERY_DISCHARGING && BATTERY_FULL_DISCHARGED) is still
> > POWER_SUPPLY_STATUS_DISCHARGING.
> > So, let's just report what the battery says and do:
> >
> >                else if (ret & BATTERY_DISCHARGING)
> >                                val->intval = POWER_SUPPLY_STATUS_DISCHARGING;
> >
> So we just ignore the special situation (BATTERY_DISCHARGING &&
> BATTERY_FULL_DISCHARGED).
> Isn't POWER_SUPPLY_STATUS_NOT_CHARGING a useful information?

The battery is discharging.  The fact that it is also reporting that
it is already "discharged" just seems premature.   I would expect to
only see NOT_CHARGING if completely discharged *and* not discharging.

>
>
> Regards,
> YH Huang
>