diff mbox series

watchdog: Handle timer wrap around

Message ID 20200224002033.17860-1-judge.packham@gmail.com
State Accepted
Commit 6d8eae9ab7d17ca3ce84c5e6e29bd452936ad407
Delegated to: Stefan Roese
Headers show
Series watchdog: Handle timer wrap around | expand

Commit Message

Chris Packham Feb. 24, 2020, 12:20 a.m. UTC
On some platforms/architectures the value from get_timer() can wrap.
This is particularly problematic when long-running code needs to measure
a time difference as is the case with watchdog_reset() which tries to
avoid tickling the watchdog too frequently.

Use time_after() from time.h instead of a plain > comparison to avoid
any issues with the time wrapping on a system that has been sitting in
u-boot for a long time.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
---

 drivers/watchdog/wdt-uclass.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

Comments

Stefan Roese Feb. 24, 2020, 11:48 a.m. UTC | #1
On 24.02.20 01:20, Chris Packham wrote:
> On some platforms/architectures the value from get_timer() can wrap.
> This is particularly problematic when long-running code needs to measure
> a time difference as is the case with watchdog_reset() which tries to
> avoid tickling the watchdog too frequently.
> 
> Use time_after() from time.h instead of a plain > comparison to avoid
> any issues with the time wrapping on a system that has been sitting in
> u-boot for a long time.
> 
> Signed-off-by: Chris Packham <judge.packham@gmail.com>

Reviewed-by: Stefan Roese <sr@denx.de>

Thanks,
Stefan
Stefan Roese March 16, 2020, 2:19 p.m. UTC | #2
On 24.02.20 01:20, Chris Packham wrote:
> On some platforms/architectures the value from get_timer() can wrap.
> This is particularly problematic when long-running code needs to measure
> a time difference as is the case with watchdog_reset() which tries to
> avoid tickling the watchdog too frequently.
> 
> Use time_after() from time.h instead of a plain > comparison to avoid
> any issues with the time wrapping on a system that has been sitting in
> u-boot for a long time.
> 
> Signed-off-by: Chris Packham <judge.packham@gmail.com>

Applied to u-boot-marvell/master.

Thanks,
Stefan
diff mbox series

Patch

diff --git a/drivers/watchdog/wdt-uclass.c b/drivers/watchdog/wdt-uclass.c
index cf1c52747397..d9e4dc7cb8a4 100644
--- a/drivers/watchdog/wdt-uclass.c
+++ b/drivers/watchdog/wdt-uclass.c
@@ -7,6 +7,7 @@ 
 #include <dm.h>
 #include <errno.h>
 #include <hang.h>
+#include <time.h>
 #include <wdt.h>
 #include <dm/device-internal.h>
 #include <dm/lists.h>
@@ -83,7 +84,7 @@  void watchdog_reset(void)
 
 	/* Do not reset the watchdog too often */
 	now = get_timer(0);
-	if (now > next_reset) {
+	if (time_after(now, next_reset)) {
 		next_reset = now + 1000;	/* reset every 1000ms */
 		wdt_reset(gd->watchdog_dev);
 	}