On 5/11/21 4:20 AM, Robin Gong wrote:
Since watchdog_ping_work is not freezable so that it maybe scheduled before
imx2_wdt_resume where watchdog clock enabled, hence, kernel will hang in
imx2_wdt_ping without clock, and then watchdog reset happen. Prevent the
above case by clearing WDOG_HW_RUNNING before suspend, and restore it with
ping in imx2_wdt_resume.
Signed-off-by: Robin Gong <yibin.gong@xxxxxxx>
---
drivers/watchdog/imx2_wdt.c | 8 ++++++++
1 file changed, 8 insertions(+)
diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
index b84f80f..d3751e9 100644
--- a/drivers/watchdog/imx2_wdt.c
+++ b/drivers/watchdog/imx2_wdt.c
@@ -357,6 +357,13 @@ static int __maybe_unused imx2_wdt_suspend(struct device *dev)
*/
__imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
imx2_wdt_ping(wdog);
+
+ /*
+ * clear WDOG_HW_RUNNING to prevent watchdog_ping_work running
+ * before imx2_wdt_resume where clock enabled, otherwise kernel
+ * will hang and watchdog reset happen then.
+ */
+ clear_bit(WDOG_HW_RUNNING, &wdog->status);
}
clk_disable_unprepare(wdev->clk);
@@ -386,6 +393,7 @@ static int __maybe_unused imx2_wdt_resume(struct device *dev)
if (imx2_wdt_is_running(wdev)) {
imx2_wdt_set_timeout(wdog, wdog->timeout);
imx2_wdt_ping(wdog);
+ set_bit(WDOG_HW_RUNNING, &wdog->status);
}
return 0;
I really don't like this; it depends on assumptions how the watchdog
core works, and it misuses WDOG_HW_RUNNING to indicate that the clock
is stopped (or that the driver is in suspend mode).
If ping doesn't work with the clock stopped, I think it would be much
better to have a flag indicating that the clock is stopped, and have
the ping function do nothing if it is called with stopped clock
(ie if suspended).
Guenter
