linux-kernel - Re: [PATCH RFT 1/2] regulator: twl: Fix the formula to calculate vsel and voltage for twl6030ldo

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Message-ID: <1342434030.4717.2.camel@phoenix>
Date:	Mon, 16 Jul 2012 18:20:30 +0800
From:	Axel Lin <axel.lin@...il.com>
To:	Rajendra Nayak <rnayak@...com>
Cc:	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Peter Ujfalusi <peter.ujfalusi@...com>,
	Liam Girdwood <lrg@...com>, linux-kernel@...r.kernel.org,
	loml <linux-omap@...r.kernel.org>
Subject: Re: [PATCH RFT 1/2] regulator: twl: Fix the formula to calculate
 vsel and voltage for twl6030ldo


> On Monday 09 July 2012 04:31 PM, Axel Lin wrote:
> > 於 一，2012-07-09 於 11:22 +0800，Axel Lin 提到：
> >> In twl6030ldo_set_voltage, current code use below formula to calculate vsel:
> >>          vsel = (min_uV/1000 - 1000)/100 + 1;
> >> This is worng because when min_uV is 1000000 uV, vsel is 1.
> >> It should be 0 in this case.
> 
> Why? Do you know of any documentation which states this?

I double check with the datasheet again now.
You are right in this. So we cannot use linear mapping for
twl6030ldo_ops here.
I'm going to send a patch to fix it, I'd appreciate if someone can
review and test it.


> > I found a problem that before commit 3e3d3be79c, the voltage tables were
> > not linear mapping. So why we can convert these voltage mapping table to
> > Voltage(in mV) = 1000mv + 100mv * (vsel - 1)?
> >
> > Did I miss something?
> 
> All voltage tables before commit '3e3d3be79c' for twl6030 regulators
> were clearly wrong. They assumed similarity with twl4030 regulators
> which was not right.

Good to know that. 
Thanks,
Axel
> 
> regards,
> Rajendra
> 
> >
> > Regards,
> > Axel
> >
> >
> 


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