From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756436AbaELMA7 (ORCPT ); Mon, 12 May 2014 08:00:59 -0400 Received: from v094114.home.net.pl ([79.96.170.134]:49889 "HELO v094114.home.net.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1755885AbaELMA6 (ORCPT ); Mon, 12 May 2014 08:00:58 -0400 From: "Rafael J. Wysocki" To: dirk.brandewie@gmail.com Cc: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, Dirk Brandewie Subject: Re: [PATCH 3/5] intel_pstate: Fix fixed point rounding macro Date: Mon, 12 May 2014 14:17:43 +0200 Message-ID: <10396519.O9MHslF7EE@vostro.rjw.lan> User-Agent: KMail/4.11.5 (Linux/3.14.0-rc7+; KDE/4.11.5; x86_64; ; ) In-Reply-To: <1399579047-5792-4-git-send-email-dirk.j.brandewie@intel.com> References: <1399579047-5792-1-git-send-email-dirk.j.brandewie@intel.com> <1399579047-5792-4-git-send-email-dirk.j.brandewie@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thursday, May 08, 2014 12:57:25 PM dirk.brandewie@gmail.com wrote: > From: Dirk Brandewie > > Change the FP_ROUNDUP macro to add 0.5 in fixed point representation > instead of 1.0 It would be good to say why exactly it is a problem too. I guess it overflows sometimes, right? > Signed-off-by: Dirk Brandewie > --- > drivers/cpufreq/intel_pstate.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c > index eab8ccf..bb20881 100644 > --- a/drivers/cpufreq/intel_pstate.c > +++ b/drivers/cpufreq/intel_pstate.c > @@ -43,7 +43,7 @@ > #define FRAC_BITS 6 > #define int_tofp(X) ((int64_t)(X) << FRAC_BITS) > #define fp_toint(X) ((X) >> FRAC_BITS) > -#define FP_ROUNDUP(X) ((X) += 1 << FRAC_BITS) > +#define FP_ROUNDUP(X) ((X) += 1 << (FRAC_BITS-1)) > > static inline int32_t mul_fp(int32_t x, int32_t y) > { > -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.