linux-kernel - Re: [PATCH v8 5/8] Loongson: YeeLoong: add hardware monitoring driver

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Message-ID: <1260183663.9092.51.camel@falcon.domain.org>
Date:	Mon, 07 Dec 2009 19:01:03 +0800
From:	Wu Zhangjin <wuzhangjin@...il.com>
To:	Pavel Machek <pavel@....cz>
Cc:	Ralf Baechle <ralf@...ux-mips.org>, akpm@...ux-foundation.org,
	linux-mips@...ux-mips.org, linux-kernel@...r.kernel.org,
	Dmitry Torokhov <dmitry.torokhov@...il.com>,
	"Rafael J . Wysocki" <rjw@...k.pl>, zhangfx@...ote.com,
	linux-laptop@...r.kernel.org,
	Stephen Rothwell <sfr@...b.auug.org.au>
Subject: Re: [PATCH v8 5/8] Loongson: YeeLoong: add hardware monitoring
 driver

On Mon, 2009-12-07 at 10:49 +0100, Pavel Machek wrote:
> 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.
> 	

Done, but any document/standard about it?

Regards,
	Wu Zhangjin

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