Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933563AbaGVWcs (ORCPT ); Tue, 22 Jul 2014 18:32:48 -0400 Received: from youngberry.canonical.com ([91.189.89.112]:44865 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932194AbaGVW0q (ORCPT ); Tue, 22 Jul 2014 18:26:46 -0400 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Gabor Juhos , Wim Van Sebroeck , Kamal Mostafa Subject: [PATCH 3.8 074/116] watchdog: ath79_wdt: avoid spurious restarts on AR934x Date: Tue, 22 Jul 2014 15:21:25 -0700 Message-Id: <1406067727-19683-75-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1406067727-19683-1-git-send-email-kamal@canonical.com> References: <1406067727-19683-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 3.8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.8.13.27 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Gabor Juhos commit 23afeb613ec0e10aecfae7838a14d485db62ac52 upstream. On some AR934x based systems, where the frequency of the AHB bus is relatively high, the built-in watchdog causes a spurious restart when it gets enabled. The possible cause of these restarts is that the timeout value written into the TIMER register does not reaches the hardware in time. Add an explicit delay into the ath79_wdt_enable function to avoid the spurious restarts. Signed-off-by: Gabor Juhos Reviewed-by: Guenter Roeck Signed-off-by: Wim Van Sebroeck Signed-off-by: Kamal Mostafa --- drivers/watchdog/ath79_wdt.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/watchdog/ath79_wdt.c b/drivers/watchdog/ath79_wdt.c index 38a999e..bb242bd 100644 --- a/drivers/watchdog/ath79_wdt.c +++ b/drivers/watchdog/ath79_wdt.c @@ -20,6 +20,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include +#include #include #include #include @@ -77,6 +78,15 @@ static inline void ath79_wdt_keepalive(void) static inline void ath79_wdt_enable(void) { ath79_wdt_keepalive(); + + /* + * Updating the TIMER register requires a few microseconds + * on the AR934x SoCs at least. Use a small delay to ensure + * that the TIMER register is updated within the hardware + * before enabling the watchdog. + */ + udelay(2); + ath79_reset_wr(AR71XX_RESET_REG_WDOG_CTRL, WDOG_CTRL_ACTION_FCR); /* flush write */ ath79_reset_rr(AR71XX_RESET_REG_WDOG_CTRL); -- 1.9.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/