References: <20091019102116.222ff9c3.peter@piie.net> <20091019091617.GA13277@rhlx01.hs-esslingen.de>
Message-ID: <cone.1255987487.209127.3188.1000@deskpiie>
From: Peter Feuerer <peter@piie.net>
To: Andreas Mohr <andi@lisas.de>
Cc: Borislav Petkov <petkovbb@gmail.com>, linux-kernel@vger.kernel.org
Subject: Re: [Patch] acerhdf: Return temperature in milidegree
Date: Mon, 19 Oct 2009 23:24:47 +0200
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Hi Andreas,

thank you very much for your brainstorming.

Andreas Mohr writes:

> Hi,
> 
> On Mon, Oct 19, 2009 at 10:21:16AM +0200, Peter Feuerer wrote:
>> 
>> Hi Boris,
>> 
>> what do you think about this patch?
> 
> Personally I'm hurting a bit due to the open-coded "* 1000" transition
> in all places.
> 
> I'd add a helper macro
> #define TEMP_DEGREE_TO_SYS(x) ((x) * 1000)
> and use that in all places where it matters.
> 
> Advantage:
> - either no mistyping (10000 instead of 1000) _or_ bug occurring in _all_
>   places where this macro is used
> - easily grepped-for
> - easily changed once the system granularity gets updated

I agree with you in these points, but I have also some disadvantages to discuss:

Disadvantages:
 - Thinking about the implemenation such a macro would require, users may 
   get confused. They would still set the fanon / fanoff trip points in 
   degree, but when they read documentation or the current temperature, 
   millidegree is used.  
 - I think "TEMP_DEGREE_TO_SYS(59)" in code is not 
   as good readable as "59000"

what about writing something like "59 * 1000" insead of "59000"?

Or something like that:

#define FACTOR_MILLIDEGREE 1000
59 * FACTOR_MILLIDEGREE 

this solution has all your listed advantages and eliminates the 
disadvantages I see in the "TEMP_DEGREE_TO_SYS" solution.

--peter
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