linux-kernel - Re: [PATCH] regulator: add driver for MAX8660/8661

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Message-Id: <1253816506.11624.889.camel@vega>
Date:	Thu, 24 Sep 2009 19:21:46 +0100
From:	Liam Girdwood <lrg@...mlogic.co.uk>
To:	Wolfram Sang <w.sang@...gutronix.de>
Cc:	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] regulator: add driver for MAX8660/8661

On Thu, 2009-09-24 at 20:07 +0200, Wolfram Sang wrote:
> > > +	if (MAX8660_DCDC_MIN_UV + selector * MAX8660_DCDC_STEP > max_uV)
> > > +		return -EINVAL;
> > 
> > Not important but using list_voltage() here would be a little nicer.
> 
> Well, uhm, yeah :)
> 
> > > +static struct regulator_ops max8660_dcdc_ops = {
> > > +	.is_enabled = max8660_dcdc_is_enabled,
> > > +	.list_voltage = max8660_dcdc_list,
> > > +	.set_voltage = max8660_dcdc_set,
> > > +	.get_voltage = max8660_dcdc_get,
> > > +	/* no set_mode() & friends: forced PWM does not save any power */
> > 
> > Forced PWM is normally a power loss - the benefit it gives is the
> > ability to respond to sudden spikes in load without voltage droops.  The
> > power benefit from not having it enabled is usually only apparent at
> > lower loads.
> 
> Understood. Well, as this chip automatically switches PWM on/off depending on
> the load (formula is in the datasheet), it seems to me that the forced-PWM mode
> is mainly used for systems which prefer low-noise on the signal. So, the above
> comment could just be dropped. Liam, could you do this, or shall I resend?

Would be easier for me if you could resend. Mark and I are at LPC today
so not really in a position to code (or even answers mails quickly).

Thanks

Liam

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