Disabling the softdevice hangs when using LFRC with an active watchdog

RE: Disabling the softdevice hangs when using LFRC with an active watchdog

fwst303 — Tue, 07 Jan 2020 16:39:30 GMT

Thanks a lot, Einar!

I like the idea of some sort of notification being returned about the driver not being able to shut down its LFCLK. Then an app could decide to ignore this or handle it as needed.

For the softdevice, if the WDT is running then caring about the LFRC getting shut down is kind of moot, so maybe some sort of error check or "if !(WDT is running && softdevice LFCLK == LFRC)" guard around the call for would suffice there.

RE: Disabling the softdevice hangs when using LFRC with an active watchdog

fwst303 — Tue, 07 Jan 2020 16:22:49 GMT

Confirmed, inserting `nrf_drv_clock_lfclk_request(NULL);` before `nrf_sdh_disable_request();` allows the softdevice disable to succeed and execution to continue. I'd prefer to use LFRC and this workaround is fine for the app, so I'll use this until something more official is introduced from Einar's report. Thanks!

RE: Disabling the softdevice hangs when using LFRC with an active watchdog

Einar Thorsrud — Tue, 07 Jan 2020 14:55:01 GMT

Hi,

I think you can see this as a bug in the clock drivers. I have reported it internally.

I am not sure exactly where this should be fixed. If you tell nrfx to disable the clock by calling nrfx_clock_lfclk_stop(), it could perhaps return an error if the watchdog is enabled, or silently handle this by not waiting for the clock to stop if the watchdog timer is ready. Alternatively, you could modify sd_state_evt_handler() to not call nrf_drv_clock_lfclk_release() on the NRF_SDH_EVT_STATE_DISABLED event as you do, or check if the WDT is enabled, and only call it if not.

RE: Disabling the softdevice hangs when using LFRC with an active watchdog

Sebastian Bøe — Tue, 07 Jan 2020 12:48:47 GMT

m_clock_cb.lfclk_requests. If the nrfx WDT driver is not registering this request. Is it possible for the application to do so?