Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [PATCH v1] watchdog: imx2_wdt: clear WDOG_HW_RUNNING before suspend | From | Guenter Roeck <> | Date | Mon, 10 May 2021 20:59:25 -0700 |
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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@nxp.com> > --- > 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
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