linux-kernel - RE: [PATCH 4/5] max17042: Fix value scaling for VCELL and avgVCELL

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Date:	Tue, 13 Mar 2012 14:04:12 -0700
From:	Jason Wortham <Jason.Wortham@...im-ic.com>
To:	bruce robertson <bruce.e.robertson@...el.com>,
	Anton Vorontsov <cbouatmailru@...il.com>
CC:	"dirk.brandewie@...il.com" <dirk.brandewie@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"dg77.kim@...sung.com" <dg77.kim@...sung.com>,
	"kyungmin.park@...sung.com" <kyungmin.park@...sung.com>,
	"myungjoo.ham@...sung.com" <myungjoo.ham@...sung.com>
Subject: RE: [PATCH 4/5] max17042: Fix value scaling for VCELL and avgVCELL

The bottom 3 bits are still functional bits and aren't required to be masked.  Arguably these bits are below the hardware accuracy of the ADC, however, they still provide some averaging information.

--Jason

-----Original Message-----
From: bruce robertson [mailto:bruce.e.robertson@...el.com] 
Sent: Tuesday, March 13, 2012 2:00 PM
To: Anton Vorontsov
Cc: dirk.brandewie@...il.com; linux-kernel@...r.kernel.org; dg77.kim@...sung.com; kyungmin.park@...sung.com; myungjoo.ham@...sung.com; Jason Wortham
Subject: Re: [PATCH 4/5] max17042: Fix value scaling for VCELL and avgVCELL

Anton Vorontsov <cbouatmailru@...il.com> writes:

> On Tue, Jan 24, 2012 at 09:26:07AM -0800, dirk.brandewie@...il.com wrote:
>> From: Bruce Robertson <bruce.e.robertson@...el.com>
>> 
>> The bottom three bits of the register are don't care bits.  The LSB
>> value is 625 uV.  Adjust the returned values appropriately
>> 
>> Signed-off-by: Bruce Robertson <bruce.e.robertson@...el.com>
>> Signed-off-by: Dirk Brandewie <dirk.brandewie@...il.com>
>> Acked-by: MyungJoo Ham <myungjoo.ham@...sung.com>
>
> I guess this was fixed long ago by the following patch:
>
> commit cf7a8c03db792894f436db5f3ffc44d947b9b068
> Author: MyungJoo Ham <myungjoo.ham@...sung.com>
> Date:   Wed Aug 17 10:18:34 2011 +0900
>
>     max17042_battery: Bugfix of incorrect voltage register value interpretation
>
>     The calculation had error in getting voltage values from
>     MAX17042 registers. The least bit denotes 78.125uV (625/8).

The multipliers I see in the patch are 83 making the voltages somewhat
high and the low 3 bits are not masked off. I'm probably misreading the code.

>
>     Signed-off-by: MyungJoo Ham <myungjoo.ham@...sung.com>
>     Signed-off-by: Philip Rakity <prakity@...vell.com>
>     Signed-off-by: Kyungmin Park <kyungmin.park@...sung.com>
>     Signed-off-by: Anton Vorontsov <cbouatmailru@...il.com>
>
> Thanks,
--
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