On some dw_wdt implementations the "top" register may be initted to 0 at bootup. In such a case, each "pat" of the watchdog will reset the timer to 0xffff. That's pretty short. The input clock of the wdt can be any of a wide range of values. On an rk3288 system, I've seen the wdt clock be 24.75 MHz. That means each tick is ~40ns and we'll count to 0xffff in ~2.6ms. Because of the above two facts, it's a really good idea to pat the watchdog after initting the "top" register properly and before enabling the watchdog. If you don't then there's no way we'll get the next heartbeat in time. Signed-off-by: Doug Anderson <dianders@xxxxxxxxxxxx> --- drivers/watchdog/dw_wdt.c | 1 + 1 file changed, 1 insertion(+) diff --git a/drivers/watchdog/dw_wdt.c b/drivers/watchdog/dw_wdt.c index b34a2e4..fc92bea 100644 --- a/drivers/watchdog/dw_wdt.c +++ b/drivers/watchdog/dw_wdt.c @@ -170,6 +170,7 @@ static int dw_wdt_open(struct inode *inode, struct file *filp) * the maximum and then start it. */ dw_wdt_set_top(DW_WDT_MAX_TOP); + dw_wdt_keepalive(); writel(WDOG_CONTROL_REG_WDT_EN_MASK, dw_wdt.regs + WDOG_CONTROL_REG_OFFSET); } -- 2.2.0.rc0.207.ga3a616c -- To unsubscribe from this list: send the line "unsubscribe linux-watchdog" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
