From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753162AbbKMHvF (ORCPT ); Fri, 13 Nov 2015 02:51:05 -0500 Received: from mx0b-0016f401.pphosted.com ([67.231.156.173]:64255 "EHLO mx0b-0016f401.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751746AbbKMHvD (ORCPT ); Fri, 13 Nov 2015 02:51:03 -0500 From: Jisheng Zhang To: , CC: , , Jisheng Zhang Subject: [PATCH] clocksource/drivers/dw_apb_timer: use {readl|writel}_relaxed Date: Fri, 13 Nov 2015 15:46:47 +0800 Message-ID: <1447400807-4706-1-git-send-email-jszhang@marvell.com> X-Mailer: git-send-email 2.6.2 MIME-Version: 1.0 Content-Type: text/plain X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2015-11-13_08:,, signatures=0 X-Proofpoint-Spam-Details: rule=inbound_notspam policy=inbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1507310000 definitions=main-1511130144 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org readl/writel is too expensive on Cortex A9 w/ outer L2 cache, especially the writel will try to hold l2x0_lock, which could increase chance of L2 cache maintance spinning at the l2x0_lock. The driver does not perform DMA, so it's safe to use the relaxed version. From another side, the relaxed io accessor macros are available on all architectures now, so we can use the relaxed versions to get a trivial overall system performance improvement on some architectures. Signed-off-by: Jisheng Zhang --- drivers/clocksource/dw_apb_timer.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/clocksource/dw_apb_timer.c b/drivers/clocksource/dw_apb_timer.c index c76c750..04282ee 100644 --- a/drivers/clocksource/dw_apb_timer.c +++ b/drivers/clocksource/dw_apb_timer.c @@ -51,13 +51,13 @@ clocksource_to_dw_apb_clocksource(struct clocksource *cs) static unsigned long apbt_readl(struct dw_apb_timer *timer, unsigned long offs) { - return readl(timer->base + offs); + return readl_relaxed(timer->base + offs); } static void apbt_writel(struct dw_apb_timer *timer, unsigned long val, unsigned long offs) { - writel(val, timer->base + offs); + writel_relaxed(val, timer->base + offs); } static void apbt_disable_int(struct dw_apb_timer *timer) -- 2.6.2