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authorBoris BREZILLON <b.brezillon@overkiz.com>2013-11-03 21:52:43 +0400
committerWim Van Sebroeck <wim@iguana.be>2014-01-29 00:34:38 +0400
commita04c3f01d33f4661424deeff67913699a0910c53 (patch)
tree0632c5a099c300fe0414244cebe8dce8ce051334 /drivers/watchdog
parent1444797fc178b58e91cf29a438efd05dd890d43a (diff)
downloadlinux-a04c3f01d33f4661424deeff67913699a0910c53.tar.xz
watchdog: at91sam9_wdt: avoid spurious watchdog reset during init
Use the min_heartbeat value instead of the calculated heartbeat value for the first watchdog reset to avoid spurious watchdog reset. Resetting the watchdog counter during init might lead to a watchdog fault reset because the watchdog counter has to be running for at least min_heartbeat. Resetting the watchdog counter after heartbeat might lead to a watchdog timeout reset because the watchdog counter is running for more than max_heartbeat time. Using min_heartbeat instead of heartbeat does not guarantee that the watchdog won't trigger a reset, but at least it reduces the chances to be in such a case. Signed-off-by: Boris BREZILLON <b.brezillon@overkiz.com> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be>
Diffstat (limited to 'drivers/watchdog')
-rw-r--r--drivers/watchdog/at91sam9_wdt.c10
1 files changed, 9 insertions, 1 deletions
diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c
index 65f469145950..ab0c4e0165d1 100644
--- a/drivers/watchdog/at91sam9_wdt.c
+++ b/drivers/watchdog/at91sam9_wdt.c
@@ -213,7 +213,15 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt)
tmp & wdt->mr_mask, wdt->mr & wdt->mr_mask);
setup_timer(&wdt->timer, at91_ping, (unsigned long)wdt);
- mod_timer(&wdt->timer, jiffies + wdt->heartbeat);
+
+ /*
+ * Use min_heartbeat the first time to avoid spurious watchdog reset:
+ * we don't know for how long the watchdog counter is running, and
+ * - resetting it right now might trigger a watchdog fault reset
+ * - waiting for heartbeat time might lead to a watchdog timeout
+ * reset
+ */
+ mod_timer(&wdt->timer, jiffies + min_heartbeat);
/* Try to set timeout from device tree first */
if (watchdog_init_timeout(&wdt->wdd, 0, dev))