linux-kernel - Re: [PATCH] power: max17042: do not lose accuracy calculating current

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Date:	Tue, 16 Aug 2011 06:12:57 +0000 (GMT)
From:	MyungJoo Ham <myungjoo.ham@...sung.com>
To:	Philip Rakity <prakity@...vell.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Cc:	Anton Vorontsov <cbouatmailru@...il.com>,
	박경민 <kyungmin.park@...sung.com>
Subject: Re: [PATCH] power: max17042: do not lose accuracy calculating
 current_now

Philip Rakity<prakity@...vell.com> Date : 2011-08-13 13:19 (GMT+09:00)
> 
> PROP_CURRENT_NOW value is first divided then multiplied up
> causing a lose of accuracy.  Use the same method as
> PROP_CURRENT_AVG to do the calculation.
> 
> Signed-off-by: Philip Rakity 

Acked-by: MyungJoo Ham <myungjoo.ham@...sung.com>

> ---
> drivers/power/max17042_battery.c |    3 +--
> 1 files changed, 1 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/power/max17042_battery.c b/drivers/power/max17042_battery.c
> index 4245806..7b7762a 100644
> --- a/drivers/power/max17042_battery.c
> +++ b/drivers/power/max17042_battery.c
> @@ -153,8 +153,7 @@ static int max17042_get_property(struct power_supply *psy,
> val->intval++;
> val->intval *= -1;
> }
> - val->intval >>= 4;
> - val->intval *= 1000000 * 25 / chip->pdata->r_sns;
> + val->intval *= 1562500 / chip->pdata->r_sns;
> } else {
> return -EINVAL;
> }
> -- 
> 1.7.0.4
> 
> 
> 



 MyungJoo Ham (함명주)
Mobile Software Platform Lab,
Digital Media and Communications (DMC) Business
Samsung Electronics
cell: +82-10-6714-2858 / office: +82-31-279-8033