Re: [PATCH 10/13] twl4030_charger: add software controlled linear charging mode.

From	Neil Brown <neil@brown.name>
Newsgroups	linux.kernel
Subject	Re: [PATCH 10/13] twl4030_charger: add software controlled linear charging mode.
Date	2015-10-01 08:20 +0200
Message-ID	<qeFnI-3O7-5@gated-at.bofh.it> (permalink)
References	<pRJTr-7hl-3@gated-at.bofh.it> <pRK38-7sx-9@gated-at.bofh.it> <q8WAW-3m7-13@gated-at.bofh.it>
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Pavel Machek <pavel@ucw.cz> writes:

> On Thu 2015-07-30 10:11:24, NeilBrown wrote:
>> 
>> Add a 'continuous' option for usb charging which enables
>> the "linear" charging mode of the twl4030.
>> 
>> Linear charging does a good job with not-so-reliable power sources.
>> Auto mode does not work well as it switches off when voltage drops
>> momentarily.  Care must be taken not to over-charge.
>
> Can you explain how the user can "care not to over-charge"?

The following text reads:

    It was used with a bike hub dynamo since a year or so. In that case
    there are automatically charging stops when the cyclist needs a break.

so: take a break from cycling occasionally.

>
>> @@ -750,6 +784,17 @@ static int twl4030_bci_get_property(struct power_supply *psy,
>>  		is_charging = state & TWL4030_MSTATEC_USB;
>>  	else
>>  		is_charging = state & TWL4030_MSTATEC_AC;
>> +	if (!is_charging) {
>> +		u8 s;
>> +		twl4030_bci_read(TWL4030_BCIMDEN, &s);
>> +		if (psy->desc->type == POWER_SUPPLY_TYPE_USB)
>> +			is_charging = s & 1;
>> +		else
>> +			is_charging = s & 2;
>> +		if (is_charging)
>> +			/* A little white lie */
>> +			state = TWL4030_MSTATEC_QUICK1;
>
> I'm not sure... can't this white lie turn into black smoke?
>
> Like.. normally, when battery is below something (like 3.5V) it must
> not be quick-charged (because something is very wrong with it). Are
> you just forcing the quick charge here?

No.  That value is only used for reporting a status via sysfs.
That 'lie' gets translated to "POWER_SUPPLY_STATUS_CHARGING" which is
not a lie.

Thanks,
NeilBrown


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

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Re: [PATCH 10/13] twl4030_charger: add software controlled linear charging mode. Neil Brown <neil@brown.name> - 2015-10-01 08:20 +0200

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