From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758853Ab3APJ2H (ORCPT ); Wed, 16 Jan 2013 04:28:07 -0500 Received: from multi.imgtec.com ([194.200.65.239]:10052 "EHLO multi.imgtec.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758688Ab3APJ2C (ORCPT ); Wed, 16 Jan 2013 04:28:02 -0500 Message-ID: <50F67299.4010102@imgtec.com> Date: Wed, 16 Jan 2013 09:27:53 +0000 From: James Hogan User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/17.0 Thunderbird/17.0 MIME-Version: 1.0 To: Mike Turquette CC: Joe Perches , , , Subject: Re: [PATCH 1/1] clk-divider: fix is_power_of_two() References: <1358245685-4392-1-git-send-email-james.hogan@imgtec.com> <1358274665.2597.11.camel@joe-AO722> <20130116005639.8920.45989@quantum> In-Reply-To: <20130116005639.8920.45989@quantum> X-Enigmail-Version: 1.4.6 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.154.65] X-SEF-Processed: 7_3_0_01181__2013_01_16_09_27_54 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 16/01/13 00:56, Mike Turquette wrote: > Quoting Joe Perches (2013-01-15 10:31:05) >> On Tue, 2013-01-15 at 10:28 +0000, James Hogan wrote: >>> The macro is_power_of_two() in clk-divider.c was defined as !(i & ~i) >>> which is always true. Correct it to !(i & (i - 1)). >> [] >>> diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c >> [] >>> @@ -29,8 +29,8 @@ >> [] >>> -#define div_mask(d) ((1 << (d->width)) - 1) >>> -#define is_power_of_two(i) !(i & ~i) >>> +#define div_mask(d) ((1 << ((d)->width)) - 1) >>> +#define is_power_of_two(i) (!((i) & ((i) - 1))) >> >> Use is_power_of_2 in log2.h instead? > > Both are fine suggestions. How about I apply the below patch? Looks good to me, thanks for taking care of the log.h change. Cheers James > From 54c6c9e5f61693effbe6e4fb28ef9f2f9b3d7a23 Mon Sep 17 00:00:00 2001 > From: James Hogan > Date: Tue, 15 Jan 2013 10:28:05 +0000 > Subject: [PATCH] clk-divider: fix macros > > The macro is_power_of_two() in clk-divider.c was defined as !(i & ~i) > which is always true. Instead use is_power_of_2() from log2.h. > > Also add brackets around the macro arguments in div_mask to avoid any > future operator precedence problems. > > Signed-off-by: James Hogan > Cc: Joe Perches > Signed-off-by: Mike Turquette > [mturquette@linaro.org: use log2.h per Joe Perches; update changelog] > --- > drivers/clk/clk-divider.c | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/drivers/clk/clk-divider.c b/drivers/clk/clk-divider.c > index a9204c6..68b4021 100644 > --- a/drivers/clk/clk-divider.c > +++ b/drivers/clk/clk-divider.c > @@ -16,6 +16,7 @@ > #include > #include > #include > +#include > > /* > * DOC: basic adjustable divider clock that cannot gate > @@ -29,8 +30,7 @@ > > #define to_clk_divider(_hw) container_of(_hw, struct clk_divider, hw) > > -#define div_mask(d) ((1 << (d->width)) - 1) > -#define is_power_of_two(i) !(i & ~i) > +#define div_mask(d) ((1 << ((d)->width)) - 1) > > static unsigned int _get_table_maxdiv(const struct clk_div_table *table) > { > @@ -137,7 +137,7 @@ static bool _is_valid_table_div(const struct clk_div_table *table, > static bool _is_valid_div(struct clk_divider *divider, unsigned int div) > { > if (divider->flags & CLK_DIVIDER_POWER_OF_TWO) > - return is_power_of_two(div); > + return is_power_of_2(div); > if (divider->table) > return _is_valid_table_div(divider->table, div); > return true; >