On Wed, Jun 16, 2021 at 03:59:23PM +0200, Grzegorz Jaszczyk wrote:

On Tue, 15 Jun 2021 at 16:18, Guenter Roeck [off-list ref] wrote:

quoted

On Tue, Jun 15, 2021 at 02:39:03PM +0200, Grzegorz Jaszczyk wrote:

quoted

The watchdog drivers often disable wdog clock during suspend and then
enable it again during resume. Nevertheless the ping worker is still
running and can issue low-level ping while the wdog clock is disabled
causing the system hang. To prevent such condition introduce
watchdog_dev_suspend/resume which can be used by any wdog driver and
actually cancel ping worker during suspend and restore it back, if
needed, during resume.

I'll have to look into this further, but I don't think this is the correct
solution. Most likely the watchdog core needs to have its own independent
suspend/resule functions and suspend the high resolution timer on
suspend and restore it on resume. This may require an additional flag
to be set by drivers to indicate that the timer should be stopped on
suspend.

That makes sense - thank you for your suggestion. I think I could
register a pm notifier in the watchdog core when the new e.g.
WDOG_STOP_PING_ON_SUSPEND status flag will be set by the driver and
actually call watchdog_dev_suspend/resume from the notifier callback.
Please let me know if you see any other issue with this solution, if
not I will post v2.

Go for it.

Thanks,
Guenter

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