@@ -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/init.h>
@@ -91,6 +92,15 @@ 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);
This is a note to let you know that I have just added a patch titled watchdog: ath79_wdt: avoid spurious restarts on AR934x to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From 6a7b67ec25f987e096cf66077f409f0ab5ca2b2e Mon Sep 17 00:00:00 2001 From: Gabor Juhos <juhosg@openwrt.org> Date: Wed, 16 Apr 2014 11:34:41 +0200 Subject: watchdog: ath79_wdt: avoid spurious restarts on AR934x commit 23afeb613ec0e10aecfae7838a14d485db62ac52 upstream. 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 <juhosg@openwrt.org> Reviewed-by: Guenter Roeck <linux@roeck-us.net> Signed-off-by: Wim Van Sebroeck <wim@iguana.be> Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/watchdog/ath79_wdt.c | 10 ++++++++++ 1 file changed, 10 insertions(+) -- 1.9.1