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

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Message-ID: <20150915112825.GA10704@amd>
Date:	Tue, 15 Sep 2015 13:28:25 +0200
From:	Pavel Machek <pavel@....cz>
To:	NeilBrown <neil@...wn.name>
Cc:	Sebastian Reichel <sre@...nel.org>,
	Samuel Ortiz <sameo@...ux.intel.com>, linux-pm@...r.kernel.org,
	Tony Lindgren <tony@...mide.com>,
	David Woodhouse <dwmw2@...radead.org>,
	linux-kernel@...r.kernel.org,
	real GTA04 owners <gta04-owner@...delico.com>,
	Dmitry Eremin-Solenikov <dbaryshkov@...il.com>,
	linux-omap@...r.kernel.org, Lee Jones <lee.jones@...aro.org>
Subject: Re: [PATCH 10/13] twl4030_charger: add software controlled linear
 charging mode.

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"?

> @@ -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?

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