From a04c3f01d33f4661424deeff67913699a0910c53 Mon Sep 17 00:00:00 2001 From: Boris BREZILLON <b.brezillon@overkiz.com> Date: Sun, 3 Nov 2013 18:52:43 +0100 Subject: [PATCH] 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> --- drivers/watchdog/at91sam9_wdt.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c index 65f469145950f..ab0c4e0165d1a 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)) -- 2.30.2