watchdog: reset last_hw_keepalive time at start

stable inclusion
from linux-4.19.119
commit ba54ddabc0135481eff2f380d424a2228d347008

--------------------------------

[ Upstream commit 982bb705 ]

Currently the watchdog core does not initialize the last_hw_keepalive
time during watchdog startup. This will cause the watchdog to be pinged
immediately if enough time has passed from the system boot-up time, and
some types of watchdogs like K3 RTI does not like this.

To avoid the issue, setup the last_hw_keepalive time during watchdog
startup.
Signed-off-by: NTero Kristo <t-kristo@ti.com>
Reviewed-by: NGuenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20200302200426.6492-3-t-kristo@ti.comSigned-off-by: NGuenter Roeck <linux@roeck-us.net>
Signed-off-by: NWim Van Sebroeck <wim@linux-watchdog.org>
Signed-off-by: NSasha Levin <sashal@kernel.org>
Signed-off-by: NYang Yingliang <yangyingliang@huawei.com>

drivers/watchdog/watchdog_dev.c

@@ -264,6 +264,7 @@ static int watchdog_start(struct watchdog_device *wdd)
 	if (err == 0) {
 		set_bit(WDOG_ACTIVE, &wdd->status);
 		wd_data->last_keepalive = started_at;
+		wd_data->last_hw_keepalive = started_at;
 		watchdog_update_worker(wdd);
 	}