linux-kernel - [PATCH] watchdog: booke_wdt: Disable the watchdog prior to setting a new timeout value in order to avoid the following situation

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Date:   Thu, 22 Mar 2018 11:51:46 +0800
From:   Xiaofeng Wei <xiaofeng.wei@....com>
To:     wim@...ana.be, linux-watchdog@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     linux@...ck-us.net, hongjun.chen@....com,
        Xiaofeng Wei <xiaofeng.wei@....com>
Subject: [PATCH] watchdog: booke_wdt: Disable the watchdog prior to setting a new timeout value in order to avoid the following situation

A watchdog timer exception also occurs if the selected time base bit transitions from 0 to 1 due
to an mtspr that writes a 1 to the bit when its previous value was 0.

Signed-off-by: Xiaofeng Wei <xiaofeng.wei@....com>
---
 drivers/watchdog/booke_wdt.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/drivers/watchdog/booke_wdt.c b/drivers/watchdog/booke_wdt.c
index 3ad1e44..70e742c 100644
--- a/drivers/watchdog/booke_wdt.c
+++ b/drivers/watchdog/booke_wdt.c
@@ -186,9 +186,15 @@ static int booke_wdt_stop(struct watchdog_device *wdog)
 static int booke_wdt_set_timeout(struct watchdog_device *wdt_dev,
 				 unsigned int timeout)
 {
+	if (watchdog_active(wdt_dev))
+		on_each_cpu(__booke_wdt_disable, NULL, 0);
+
 	wdt_dev->timeout = timeout;
 	booke_wdt_set(wdt_dev);
 
+	if (watchdog_active(wdt_dev))
+		on_each_cpu(__booke_wdt_enable, wdt_dev, 0);
+
 	return 0;
 }
 
-- 
2.9.3