On some AR934x based systems, where the frequency of the AHB bus is relatively high, the built-in watchdog causes a spurious restart when it gets enabled.
The possible cause of these restarts is that the timeout value written into the TIMER register does not reaches the hardware in time. Add an explicit delay into the ath79_wdt_enable function to avoid the spurious restarts. Signed-off-by: Gabor Juhos <[email protected]> Cc: <[email protected]> --- drivers/watchdog/ath79_wdt.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/drivers/watchdog/ath79_wdt.c b/drivers/watchdog/ath79_wdt.c index 399c3fd..0e67d96 100644 --- a/drivers/watchdog/ath79_wdt.c +++ b/drivers/watchdog/ath79_wdt.c @@ -20,6 +20,7 @@ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/bitops.h> +#include <linux/delay.h> #include <linux/errno.h> #include <linux/fs.h> #include <linux/io.h> @@ -90,6 +91,15 @@ static inline void ath79_wdt_keepalive(void) static inline void ath79_wdt_enable(void) { ath79_wdt_keepalive(); + + /* + * Updating the TIMER register requires a few microseconds + * on the AR934x SoCs at least. Use a small delay to ensure + * that the TIMER register is updated within the hardware + * before enabling the watchdog. + */ + udelay(2); + ath79_wdt_wr(WDOG_REG_CTRL, WDOG_CTRL_ACTION_FCR); /* flush write */ ath79_wdt_rr(WDOG_REG_CTRL); -- 1.7.10 -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
