Re: [PATCH] watchdog: max77620: Add support for watchdog timer

[Laxman Dewangan]

On Wednesday 08 June 2016 06:45 PM, Guenter Roeck wrote:
> On 06/08/2016 01:58 AM, Laxman Dewangan wrote:
> > Hi Guenter,
> >
> > Thanks for quick review. I will take care of most of comment.
> > I have one query fr following comment.
> >
> > Thanks,
> > Laxman
> >
> > On Tuesday 07 June 2016 11:26 PM, Guenter Roeck wrote:
> > > Hi,
> > >
> > > On Mon, Jun 06, 2016 at 05:22:44PM +0530, Laxman Dewangan wrote:
> > > +    /* Stop watchodog */
> > > +    ret = regmap_update_bits(wdt->rmap, MAX77620_REG_CNFGGLBL2,
> > > +                 MAX77620_WDTEN, 0);
> > > +    if (ret < 0) {
> > > +        dev_err(wdt->dev, "Failed to reset WDTEN: %d\n", ret);
> > > +        return ret;
> > > +    }
> > > Alternatively, you could set WDOG_HW_RUNNING to tell the watchdog core
> > > that the watchdog is already running. The watchdog core would then ping
> > > the watchdog until the watchdog device is opened.
> > >
> > > That would also require to tell the watchdog core about the current 
> > > (or default)
> > > timeout, which doesn't seem to be set anywhere. That means it won't 
> > > be set at all
> > > unless user space updates it explicitly. This is quite unusual. Is 
> > > it on purpose
> > > or an oversight ? If it is on purpose, please explain.
> >
> > OK, we have use cases where we have enabled the WDT in BL also. and 
> > keep runnign till kernel up.
> > Instead of stopping WDT, I can say that WDOG_HW_RUNING and current 
> > timeout can be read from the register.
> >
> > Now, the WDT need to be ping periodically. Is there any flag which 
> > enabled the worker thread from core which will keep pinging till user 
> > space alive and activate the WDT?
> The watchdog core will start the worker if WDOG_HW_RUNNING is set.

Thanks, found that I also need to set max_hw_heartbeat_ms  for periodic 
ping if user space is not active.
I tested this path and it works perfectly. This is also great that all 
work thread is moved to core. It simplify the drivers very much.

I sent the v2 patch with fixing all this.

Thanks,
Laxman