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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>
This commit is contained in:
Boris BREZILLON 2013-11-03 18:52:43 +01:00 committed by Wim Van Sebroeck
parent 1444797fc1
commit a04c3f01d3
1 changed files with 9 additions and 1 deletions
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10
drivers/watchdog/at91sam9_wdt.c
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@ -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))