Messages in this thread | | | Date | Wed, 7 Jun 2017 21:50:23 +0200 | From | Pavel Machek <> | Subject | Re: [PATCH 5/5] power: supply: bq27xxx: Correct supply status with current draw |
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Hi!
> On Wed, 2017-06-07 at 09:52 +0200, Pavel Machek wrote: > > > [0]: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/comm > > > it/? > > > 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. > > Well, I couldn't really find much except the following from Documentation/ > (which is not that helpful, and the BATTERY_STATUS_* don't seem to exist > anymore): > > " STATUS - this attribute represents operating status (charging, full, > discharging (i.e. powering a load), etc.). This corresponds to > BATTERY_STATUS_* values, as defined in battery.h. " > > Generally speaking, I think the question to be asked is what information users > will be interested in in each scenario we have to consider.
Hmm. We really should add some documentation :-(.
> > 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. > > That makes sense. Note that this patch was however designed to solve the problem > the other way round: my device will report full battery when the PSU was > disconnected and that it is, in fact, drawing significant current.
That is documented / correct behaviour sometimes. Thinkpad batteries have thresholds -- lets say 100% and 95%. They charge battery to full (as expected), but then they won't start charging battery again unless it drops below 95%. So you can have "battery full, charger disconnected" state.
[Design like this prolongs longevity of li-ion batteries.]
> > And I'm not sure what this is supposed to do, but its quite strange > > code. > > Could you comment on what is strange about it? This function corrects the status > based on the current flow as explained through this thread. > > > +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;
The last line ... is strange. Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html [unhandled content-type:application/pgp-signature] | |