Re: [PATCH v2 2/3] watchdog: stm32_iwdg: Add pretimeout support

[Marek Vasut]

On 8/6/23 16:19, Guenter Roeck wrote:
> On Wed, May 17, 2023 at 09:43:48PM +0200, Marek Vasut wrote:
> > The STM32MP15xx IWDG adds registers which permit this IP to generate
> > pretimeout interrupt. This interrupt can also be used to wake the CPU
> > from suspend. Implement support for generating this interrupt and let
> > userspace configure the pretimeout. In case the pretimeout is not
> > configured by user, set pretimeout to half of the WDT timeout cycle.

[...]

> >   static int stm32_iwdg_probe(struct platform_device *pdev)
> >   {
> >   	struct device *dev = &pdev->dev;
> > @@ -253,6 +340,11 @@ static int stm32_iwdg_probe(struct platform_device *pdev)
> >   	wdd->max_hw_heartbeat_ms = ((RLR_MAX + 1) * wdt->data->max_prescaler *
> >   				    1000) / wdt->rate;
> >   
> > +	/* Initialize IRQ, this might override wdd->info, hence it is here. */
> > +	ret = stm32_iwdg_irq_init(pdev, wdt);
> > +	if (ret)
> > +		return ret;
> > +
>
> What if the interrupt fires for whatever reason and the watchdog
> isn't registered yet and the driver data is not set and the
> watchdog core doesn't know about the watchdog ?

That cannot happen since the pretimeout IRQ was not configured yet.
That can only happen once the core is aware of the WDT and calls 
set_pretimeout .