linux-kernel - Re: [PATCH 2/3] power/ds2760_battery: make charge_now and charge

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Message-ID: <20100511172003.GA19937@oksana.dev.rtsoft.ru>
Date:	Tue, 11 May 2010 21:20:03 +0400
From:	Anton Vorontsov <cbouatmailru@...il.com>
To:	Daniel Mack <daniel@...aq.de>
Cc:	linux-kernel@...r.kernel.org, Matt Reimer <mreimer@...p.net>,
	Evgeniy Polyakov <zbr@...emap.net>, Tejun Heo <tj@...nel.org>,
	David Woodhouse <dwmw2@...radead.org>,
	Andres Salomon <dilinger@...labora.co.uk>,
	Alexey Starikovskiy <astarikovskiy@...e.de>,
	Len Brown <len.brown@...el.com>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>
Subject: Re: [PATCH 2/3] power/ds2760_battery: make charge_now and
 charge_full writeable

On Tue, May 11, 2010 at 06:38:45PM +0200, Daniel Mack wrote:
[...]
> +static int ds2760_battery_set_property(struct power_supply *psy,
> +				       enum power_supply_property psp,
> +				       const union power_supply_propval *val)
> +{
> +	int ret = -EPERM;
> +	unsigned char tmp;
> +	struct ds2760_device_info *di = to_ds2760_device_info(psy);
> +
> +	switch (psp) {
> +	case POWER_SUPPLY_PROP_CHARGE_FULL:
> +		/* the interface counts in uAh, convert the value */
> +		ds2760_battery_write_rated_capacity(di, (val->intval / 1000L) /
> +							RATED_CAPACITY_FACTOR);

OK, Mark hinted that you should not change rated (design)
capacity, ever. You've made CHARGE_FULL writable, which now
actually changes CHARGE_FULL_DESIGN (which reports
rated_capacity). Obviously, this isn't acceptable.

I understand that you might want to change rated capacity for
your custom battery setups, and that's fine. After all, it's
your hardware, and you have a right to break it. :-)

But to do so,

1. Could you at least change this back to
   POWER_SUPPLY_PROP_CHARGE_FULL_DESIGN, so it'll be clear what
   exactly this prop is actually changing, and

2. Can we introduce Kconfig symbol BATTERY_DS2760_UNSAFE_OPS,
   and put an #ifdefs for this property? It should be
   'default n', of course. Plus we can #ifdef the rated_capacity
   module param as well.

Thanks!

-- 
Anton Vorontsov
email: cbouatmailru@...il.com
irc://irc.freenode.net/bd2
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