Suspend routine disables wdog clk. Nevertheless, the watchdog subsystem
is not aware of that and can still try to ping wdog through
watchdog_ping_work. In order to prevent such condition and therefore
prevent from system hang (caused by the wdog register access issued
while the wdog clock is disabled) take advantage of
watchdog_dev_suspend/resume routines which will take care of watchdog
ping worker cancel and restore.
Additionally remove hw ping from suspend/resume since it will be
issued by watchdog_dev_suspend/resume routines.
Signed-off-by: Michal Koziel <michal.koziel@xxxxxxxxxx>
Signed-off-by: Grzegorz Jaszczyk <grzegorz.jaszczyk@xxxxxxxxxx>
---
drivers/watchdog/imx2_wdt.c | 20 +++++++++++++++-----
1 file changed, 15 insertions(+), 5 deletions(-)
diff --git a/drivers/watchdog/imx2_wdt.c b/drivers/watchdog/imx2_wdt.c
index b84f80f7d342..24e3a4d2b529 100644
--- a/drivers/watchdog/imx2_wdt.c
+++ b/drivers/watchdog/imx2_wdt.c
@@ -348,6 +348,17 @@ static int __maybe_unused imx2_wdt_suspend(struct device *dev)
{
struct watchdog_device *wdog = dev_get_drvdata(dev);
struct imx2_wdt_device *wdev = watchdog_get_drvdata(wdog);
+ int ret;
+
+ /*
+ * Before disabling clk we need to notify wdog subsystem that HW wdog
+ * is being suspended. This e.g. prevents watchdog_ping_work to fire
+ * when the clk is disabled, which would result with system hang caused
+ * by wdog register access while wdog clock is disabled.
+ */
+ ret = watchdog_dev_suspend(wdog);
+ if (ret)
+ return ret;
/* The watchdog IP block is running */
if (imx2_wdt_is_running(wdev)) {
@@ -356,7 +367,6 @@ static int __maybe_unused imx2_wdt_suspend(struct device *dev)
* during resume.
*/
__imx2_wdt_set_timeout(wdog, IMX2_WDT_MAX_TIME);
- imx2_wdt_ping(wdog);
}
clk_disable_unprepare(wdev->clk);
@@ -383,12 +393,12 @@ static int __maybe_unused imx2_wdt_resume(struct device *dev)
*/
imx2_wdt_setup(wdog);
}
- if (imx2_wdt_is_running(wdev)) {
+ if (imx2_wdt_is_running(wdev))
imx2_wdt_set_timeout(wdog, wdog->timeout);
- imx2_wdt_ping(wdog);
- }
- return 0;
+ ret = watchdog_dev_resume(wdog);
+
+ return ret;
}
static SIMPLE_DEV_PM_OPS(imx2_wdt_pm_ops, imx2_wdt_suspend,
--
2.29.0
