[aspeed_wdt] watchdog is auto-pinged by kernel thread

[Kitsok]

Watchdog is pinged by system thread (watchdogd) if it's either active or running, this code is implemented in watchdog_dev.c in watchdog_ping function:

if (!watchdog_active(wdd) && !watchdog_hw_running(wdd))
                return 0;

The hardware driver synchronizes the status field of the device structure to the actual hardware status:

if (readl(wdt->base + WDT_CTRL) & WDT_CTRL_ENABLE)  {
                /*
                 * The watchdog is running, but invoke aspeed_wdt_start() to
                 * write wdt->ctrl to WDT_CTRL to ensure the watchdog's
                 * configuration conforms to the driver's expectations.
                 * Primarily, ensure we're using the 1MHz clock source.
                 */
                aspeed_wdt_start(&wdt->wdd);
                set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
        }

The issue here is that if we start the wdt in u-boot to protect from kernel hang or damaged ROFS, the kernel will ping the watchdog, so we loose the protection.

Looks like the WDOG_ACTIVE should also be set here:

                set_bit(WDOG_HW_RUNNING, &wdt->wdd.status);
+                set_bit(WDOG_ACTIVE, &wdt->wdd.status);