[PATCH v2 7/8] watchdog: starfive-wdt: Stop ping worker on system suspend

[Guenter Roeck <linux@roeck-us.net>]

When early_enable=1 is set and CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is
enabled, watchdog_register_device() starts the watchdog core hrtimer so the
non-freezable watchdogd kthread worker periodically pings the hardware
before userspace opens /dev/watchdog.

Because starfive_wdt_probe() does not call watchdog_stop_ping_on_suspend(),
WDOG_NO_PING_ON_SUSPEND is not set and the watchdog core does not cancel
its hrtimer and ping work across system suspend. After
starfive_wdt_suspend() stops the counter and calls
pm_runtime_force_suspend() to gate core_clk and apb_clk, WDOG_HW_RUNNING
remains set; if the timer fires before starfive_wdt_resume() re-enables
the clocks, watchdog_ping_work() invokes starfive_wdt_keepalive() with
gated clocks and causes an unclocked MMIO bus fault.

Call watchdog_stop_ping_on_suspend() in starfive_wdt_probe() so the
watchdog core cancels its ping timer and work in PM_SUSPEND_PREPARE before
clocks are gated and resumes pinging in PM_POST_SUSPEND after clocks are
restored.

Fixes: db728ea9c7be ("drivers: watchdog: Add StarFive Watchdog driver")
Cc: Xingyu Wu <xingyu.wu@starfivetech.com>
Cc: Ziv Xu <ziv.xu@starfivetech.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v2: New patch

 drivers/watchdog/starfive-wdt.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/watchdog/starfive-wdt.c b/drivers/watchdog/starfive-wdt.c
index 60a97ffa940a..ae2d84ccc76f 100644
--- a/drivers/watchdog/starfive-wdt.c
+++ b/drivers/watchdog/starfive-wdt.c
@@ -494,6 +494,7 @@ static int starfive_wdt_probe(struct platform_device *pdev)
 	watchdog_set_nowayout(&wdt->wdd, nowayout);
 	watchdog_stop_on_reboot(&wdt->wdd);
 	watchdog_stop_on_unregister(&wdt->wdd);
+	watchdog_stop_ping_on_suspend(&wdt->wdd);
 
 	if (early_enable) {
 		ret = starfive_wdt_start(wdt);
-- 
2.45.2