From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754646Ab2H2TFo (ORCPT ); Wed, 29 Aug 2012 15:05:44 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:60790 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754130Ab2H2TFj (ORCPT ); Wed, 29 Aug 2012 15:05:39 -0400 From: anish kumar To: cw00.choi@samsung.com, myungjoo.ham@samsung.com Cc: linux-kernel@vger.kernel.org, anish kumar Subject: [PATCH 2/2] [2/2] extcon: optimising the check_mutually_exclusive function Date: Thu, 30 Aug 2012 00:35:10 +0530 Message-Id: <1346267110-29479-2-git-send-email-anish198519851985@gmail.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1346267110-29479-1-git-send-email-anish198519851985@gmail.com> References: <1346267110-29479-1-git-send-email-anish198519851985@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: anish kumar Rather than re-inventing the wheel we can use the hamming function to calculate the number of bits set to check for violation of exclusivity. Signed-off-by: anish kumar --- drivers/extcon/extcon-class.c | 14 +++++--------- 1 files changed, 5 insertions(+), 9 deletions(-) diff --git a/drivers/extcon/extcon-class.c b/drivers/extcon/extcon-class.c index e09a6c3..06df95a 100644 --- a/drivers/extcon/extcon-class.c +++ b/drivers/extcon/extcon-class.c @@ -89,17 +89,13 @@ static int check_mutually_exclusive(struct extcon_dev *edev, u32 new_state) return 0; for (i = 0; edev->mutually_exclusive[i]; i++) { - int count = 0, j; + int weight; u32 correspondants = new_state & edev->mutually_exclusive[i]; - u32 exp = 1; - - for (j = 0; j < 32; j++) { - if (exp & correspondants) - count++; - if (count > 1) - return i + 1; - exp <<= 1; - } + + /* calculate the total number of bits set */ + weight = hweight32(correspondants); + if (weight > 1) + return i + 1; } return 0; -- 1.7.1