linux-kernel - RE: LKML - Battery charge current issue

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Message-ID: <C3AE124F08223B42BC95AEB82F0F6CED0212D4@KCHJEXMB01.kpit.com>
Date:	Mon, 19 Sep 2011 11:15:13 +0000
From:	Ashish Jangam <Ashish.Jangam@...tcummins.com>
To:	Mark Brown <broonie@...nsource.wolfsonmicro.com>
CC:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"linaro-dev@...ts.linaro.org" <linaro-dev@...ts.linaro.org>
Subject: RE: LKML - Battery charge current issue


> -----Original Message-----
> From: Mark Brown [mailto:broonie@...nsource.wolfsonmicro.com]
> Sent: Monday, September 19, 2011 3:56 PM
> To: Ashish Jangam
> Subject: Re: LKML - Battery charge current issue
> 
> On Mon, Sep 19, 2011 at 06:26:10AM +0000, Ashish Jangam wrote:
> 
> Questions like this should always be CCed to the list.
> 
> > Some Power Management Controllers has a feature of configuring battery
> > charge current for faster battery charging.
> 
> > In the Linux power supply core there is no provision that can help the user
> > for configuring battery charge current at "runtime". In current Linux
> implementation
> > this is done in battery "probe" probably using platform data.
> 
> > Should an additional entry in sysfs be added for configuring battery charge
> current
> > since most of our clients desire such feature?
> 
> This depends what you're looking to do.  The specific currents used
> should be configured using platform data, if the user gets these wrong
> they can result in physical damage to the system so it's generally
> undesirable to have userspace poking at them.  The switch from trickle
> to fast charge is normally managed automatically, often by hardware.
> If there's absolutely no way to figure this out from kernel I guess a
> userspace control would be OK but it'd be pretty surprising.

Hardware that don't support/have automatic upgrade then, quick battery charge feature
will be of no use to end user and especially in smart phone this could be problematic.

If sysfs is not a good way of doing this then some alternate mechanism will be very much
appreciated.