From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756780AbYERVrT (ORCPT ); Sun, 18 May 2008 17:47:19 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751166AbYERVrG (ORCPT ); Sun, 18 May 2008 17:47:06 -0400 Received: from ug-out-1314.google.com ([66.249.92.172]:58683 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751818AbYERVrE (ORCPT ); Sun, 18 May 2008 17:47:04 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=date:from:to:cc:subject:message-id:reply-to:references:mime-version:content-type:content-disposition:content-transfer-encoding:in-reply-to:user-agent; b=VTZUxgdOacF5FD+vPTVP6eQGr725hL1Bn/NwBEu6CS3UZWAXK8kUSCbmWH8sXUi6/Sj2BJqsYmZ/+8kIIHi12/aZHgrCko3lNgwMTadeNXg/8JI3rMN23jkH2lcHX+d6qGUR7u3+Yb/vKKV2VTJbpdSVRoUuYO3EBWn7MbR06Xc= Date: Mon, 19 May 2008 01:46:56 +0400 From: Anton Vorontsov To: Andres Salomon Cc: richard@laptop.org, avorontsov@ru.mvista.com, Andrew Morton , cbou@mail.ru, linux-kernel@vger.kernel.org, dwmw2@infradead.org Subject: Re: [PATCH] power_supply: add CHARGE_COUNTER property and olpc_battery support for it Message-ID: <20080518214656.GA16808@zarina> Reply-To: cbouatmailru@gmail.com References: <20080508003454.722ba511@ephemeral> <20080508105145.GA32017@polina.dev.rtsoft.ru> <20080508130102.3218f1e9@ephemeral> <20080508171320.GA8226@polina.dev.rtsoft.ru> <48234C25.4040807@laptop.org> <20080508193614.GA31188@polina.dev.rtsoft.ru> <4823663B.6060409@laptop.org> <20080512214629.443a5999@ephemeral> <4829A39F.7050308@laptop.org> <20080513122330.4c81e289@ephemeral> MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20080513122330.4c81e289@ephemeral> User-Agent: Mutt/1.5.17+20080114 (2008-01-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, May 13, 2008 at 12:23:30PM -0400, Andres Salomon wrote: > On Tue, 13 May 2008 10:20:15 -0400 > "Richard A. Smith" wrote: > > > Andres Salomon wrote: > > > > > + ec_word = be16_to_cpu(ec_word); > > > + val->intval = ec_word * 4167 / 10; > > > > Whats wrong with: > > > > > + val->intval = ((int)ec_word) * 6250 / 15; > > > > Which does not have overflow problems and keeps more precision. > > > > You're right, of course. Anton, can you please apply the following? Sorry for the delay... Applied, thanks! > Subject: [PATCH] power_supply: fix up CHARGE_COUNTER output to be more precise > > As Richard Smith pointed out, ACR * 6250 / 15 provides for less precision > loss than ACR * 4167 / 10, _and_ it doesn't overflow. Switch to using > that equation for CHARGE_COUNTER. > > Signed-off-by: Andres Salomon > --- > drivers/power/olpc_battery.c | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/power/olpc_battery.c b/drivers/power/olpc_battery.c > index a928165..f5d712a 100644 > --- a/drivers/power/olpc_battery.c > +++ b/drivers/power/olpc_battery.c > @@ -19,7 +19,7 @@ > > #define EC_BAT_VOLTAGE 0x10 /* uint16_t, *9.76/32, mV */ > #define EC_BAT_CURRENT 0x11 /* int16_t, *15.625/120, mA */ > -#define EC_BAT_ACR 0x12 /* int16_t, *416.7, µAh */ > +#define EC_BAT_ACR 0x12 /* int16_t, *6250/15, µAh */ > #define EC_BAT_TEMP 0x13 /* uint16_t, *100/256, °C */ > #define EC_AMB_TEMP 0x14 /* uint16_t, *100/256, °C */ > #define EC_BAT_STATUS 0x15 /* uint8_t, bitmask */ > @@ -295,7 +295,7 @@ static int olpc_bat_get_property(struct power_supply *psy, > return ret; > > ec_word = be16_to_cpu(ec_word); > - val->intval = ec_word * 4167 / 10; > + val->intval = ec_word * 6250 / 15; > break; > case POWER_SUPPLY_PROP_SERIAL_NUMBER: > ret = olpc_ec_cmd(EC_BAT_SERIAL, NULL, 0, (void *)&ser_buf, 8); > -- > 1.5.5.1 -- Anton Vorontsov email: cbouatmailru@gmail.com irc://irc.freenode.net/bd2