Date: Mon, 7 Dec 2009 10:49:10 +0100
From: Pavel Machek <pavel@ucw.cz>
To: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: Ralf Baechle <ralf@linux-mips.org>, akpm@linux-foundation.org,
       linux-mips@linux-mips.org, linux-kernel@vger.kernel.org,
       Dmitry Torokhov <dmitry.torokhov@gmail.com>,
       "Rafael J . Wysocki" <rjw@sisk.pl>, zhangfx@lemote.com,
       linux-laptop@vger.kernel.org, Stephen Rothwell <sfr@canb.auug.org.au>
Subject: Re: [PATCH v8 5/8] Loongson: YeeLoong: add hardware monitoring
 driver
Message-ID: <20091207094909.GD23088@elf.ucw.cz>
References: <cover.1260082252.git.wuzhangjin@gmail.com>
 <d8789fa7e97d8a170c4e2516d7ef2d2fbbe42cc6.1260082252.git.wuzhangjin@gmail.com>
 <20091206084717.GD2766@ucw.cz>
 <1260147298.3126.2.camel@falcon.domain.org>
 <20091207080446.GB23088@elf.ucw.cz>
 <1260178870.9092.34.camel@falcon.domain.org>
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On Mon 2009-12-07 17:41:10, Wu Zhangjin wrote:
> On Mon, 2009-12-07 at 09:04 +0100, Pavel Machek wrote:
> > > > What is going on here? I thought the value is already in two's
> > > > complement... Is the above equivalent of
> > > > 
> > > > 	      if (value < 0)
> > > > 	      	 value = -value; 
> > > > 
> > > > ? If so, why? If not, can you add a comment?
> > > 
> > > Right, then, will use this instead:
> > > 
> > > static int get_battery_current(void)
> > > { 
> > > 	s16 value;
> > > 
> > > 	value = (ec_read(REG_BAT_CURRENT_HIGH) << 8) |
> > > 		(ec_read(REG_BAT_CURRENT_LOW));
> > > 
> > > 	return abs(value);
> > > }
> > 
> > That's certainly better. But... why not return signed value? Current
> > flowing from the battery is certainly very different from current
> > flowing into it...
> 
> You are totally right ;)
> 
> Just test it, when flowing from the battery, the value is negative, and
> when flowing into the battery, the value is positive, so, no abs()
> needed. thanks!

Make it return -value, then. I believe other code uses >0 values for
discharge.
									Pavel

-- 
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