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From: Guenter Roeck <guenter.roeck@ericsson.com>
To: lm-sensors@vger.kernel.org
Subject: Re: [lm-sensors] [PATCH 0/3] hwmon: More LM63 enhancements
Date: Wed, 23 Nov 2011 20:51:49 +0000	[thread overview]
Message-ID: <20111123205149.GA26543@ericsson.com> (raw)
In-Reply-To: <1321994400-29295-1-git-send-email-guenter.roeck@ericsson.com>

On Wed, Nov 23, 2011 at 03:34:29PM -0500, Jean Delvare wrote:
> Hi Guenter,
> 
> On Tue, 22 Nov 2011 12:39:57 -0800, Guenter Roeck wrote:
> > Add support for unsigned temperatures on LM96163
> > Add support for writing remote T_CRIT limit
> > Add support for writing conversion rate register
> > 
> > Question:
> >   Calculations are currently along the line of "/ 125 * 32", causing loss of accuracy.
> >   Ok to change to "* 32 / 125" ?
> 
> I think this is on purpose. Multiplying last guarantees that we don't
> try to set bits which do not exist to 1. As long as proper rounding is
> done before dividing, I don't quite see how we could be losing
> accuracy. Do you have an actual example?
> 
You are right. I didn't realize that "/ 125" reduces accuracy to 1/8 degree C, which is exactly
what the chips support, and that "* 32" simply shifts the value left by 5 bit to match the 11-bit
registers.

Sorry for the noise.

Guenter

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      parent reply	other threads:[~2011-11-23 20:51 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2011-11-22 20:39 [lm-sensors] [PATCH 0/3] hwmon: More LM63 enhancements Guenter Roeck
2011-11-23 20:34 ` Jean Delvare
2011-11-23 20:51 ` Guenter Roeck [this message]

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