linux-kernel - Re: [PATCH 5/5] power: supply: bq27xxx: Correct supply status with current draw

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Message-ID: <20170607075218.GA6268@amd>
Date:   Wed, 7 Jun 2017 09:52:18 +0200
From:   Pavel Machek <pavel@....cz>
To:     Paul Kocialkowski <contact@...lk.fr>
Cc:     linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Pali Rohár <pali.rohar@...il.com>,
        "Andrew F . Davis" <afd@...com>,
        Sebastian Reichel <sre@...nel.org>,
        Chris Lapa <chris@...a.com.au>,
        Matt Ranostay <mranostay@...il.com>
Subject: Re: [PATCH 5/5] power: supply: bq27xxx: Correct supply status with
 current draw

Hi!

> > > I'd pass to userspace what the controller reports. Yes, I seldom see
> > > "STATUS_FULL" but that may be a problem we need to track down.
> > 
> > The controller is known, from my experience, to not be reliable in that
> > regard,
> > so I don't think it makes sense to pass a state that doesn't reflect the
> > actual
> > state of charging just because the chip tells us so.
> > 
> > Worst case, we could also have a dt property to enable that kind of fixup
> > workaround and let every device maintainer decide whether it is relevant for
> > their device.
> 
> Actually, since a similar fix[0] was accepted in sbs-battery, I'd rather not
> make this optional but rather make it the default and perhaps have a dt prop to
> disable it.
> 
> [0]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?
> h=v4.12-rc4&id=7f93e1fa032bb5ee19b868b9649bc98c82553003

Is there some documentation that explains what different power supply
statuses mean? Because without that, we can have long and useless
discussions.

If you have 40Wh battery, and you are charging it with 1mW, I don't
believe you should be indicating "charging". That battery is
full. Yes, even full batteries are sometimes charged with very low
currents to keep them full.

And I'm not sure what this is supposed to do, but its quite strange
code.

+static int sbs_status_correct(struct i2c_client *client, int *intval)
+{
+	int ret;
+
+	ret = sbs_read_word_data(client, sbs_data[REG_CURRENT].addr);
+	if (ret < 0)
+	   return ret;
+
+	ret = (s16)ret;
+

Best regards,
								Pavel
-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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