From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752818Ab1GOPEa (ORCPT ); Fri, 15 Jul 2011 11:04:30 -0400 Received: from dsl-67-204-24-19.acanac.net ([67.204.24.19]:33255 "EHLO mail.ellipticsemi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752019Ab1GOPE1 (ORCPT ); Fri, 15 Jul 2011 11:04:27 -0400 From: Nick Bowler To: linux-arm-kernel@lists.infradead.org, linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org Cc: Russell King , Wim Van Sebroeck Subject: [PATCH 3/3] watchdog: sp805: Flush posted writes in enable/disable. Date: Fri, 15 Jul 2011 11:04:02 -0400 Message-Id: <1310742242-14647-4-git-send-email-nbowler@elliptictech.com> X-Mailer: git-send-email 1.7.3.4 In-Reply-To: <1310742242-14647-1-git-send-email-nbowler@elliptictech.com> References: <1310742242-14647-1-git-send-email-nbowler@elliptictech.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There are no reads in these functions, so if MMIO writes are posted, the writes in enable/disable may not have completed by the time these functions return. If the functions run from different CPUs, it's in theory possible for the writes to be interleaved, which would be disastrous for this driver. At the very least, we need an mmiowb() before releasing the lock, but since it seems desirable for the watchdog timer to be actually stopped or reset when these functions return, read the lock register to force the writes out. Signed-off-by: Nick Bowler --- drivers/watchdog/sp805_wdt.c | 4 ++++ 1 files changed, 4 insertions(+), 0 deletions(-) diff --git a/drivers/watchdog/sp805_wdt.c b/drivers/watchdog/sp805_wdt.c index c1e099a..cc2cfbe 100644 --- a/drivers/watchdog/sp805_wdt.c +++ b/drivers/watchdog/sp805_wdt.c @@ -134,6 +134,8 @@ static void wdt_enable(void) writel(INT_ENABLE | RESET_ENABLE, wdt->base + WDTCONTROL); writel(LOCK, wdt->base + WDTLOCK); + /* Flush posted writes. */ + readl(wdt->base + WDTLOCK); spin_unlock(&wdt->lock); } @@ -146,6 +148,8 @@ static void wdt_disable(void) writel(0, wdt->base + WDTCONTROL); writel(LOCK, wdt->base + WDTLOCK); + /* Flush posted writes. */ + readl(wdt->base + WDTLOCK); spin_unlock(&wdt->lock); } -- 1.7.3.4