Re: [PATCH 2/2] mfd: da9063: fix watchdog ping execution

[Marco Felsch <m.felsch@pengutronix.de>]

Hi Ahmad,

On 19-11-04 10:57, Ahmad Fatoum wrote:
> Hello Marco,
> 
> On 11/4/19 10:44 AM, Marco Felsch wrote:
> >> This means that your boot time would increase by 200 ms. If this matter to you,
> >> you might want to change this, so watchdog_set_timeout is called only once.
> > 
> > Increasing the delay isn't a big deal. But after we discussed it again I
> > will send a v2 which handles the to fast pings by dropping those.
> 
> That would be an option too, but moving watchdog_set_timeout out of boot_entry
> would benefit other platforms too.

Hm.. I don't have a strong opinion about that. To me it seems correct to
handle the boot-watchdog within the boot_entry() function and the
callers don't need to setup it. Anyway v2 is coming ;)

Regards,
  Marco

> >> And if you do so, you could drop this patch. The only other places that feed
> >> the watchdog are the watchdog poller and the wd command. The watchdog poller
> >> already waits 500 ms between pings and the command is meant for debugging/testing.
> >> If someone wants to feed the watchdog that fast while testing, why prevent them?
> > 
> > Becuase if the watchdog gets feeded to fast then the system gets
> > reseted. So dropping the patch isn't a option.
> 
> If you move watchdog_set_timeout out of boot_entry, you'll only be able to feed the
> watchdog too fast if you manually type wd 1; wd 1;, which I argue isn't really an issue
> IMHO, but I am fine with what you implement either way.
> 
> > 
> >> (I assume you don't need to wait 200 ms between ping and disabling WDT, if you do,
> >>  one more place is the .priority watchdog device parameter in barebox-next
> > 
> > Sorry, I don't get this. You don't need to wait 200ms between ping and
> > disabling.
> 
> Just wanted to make sure that disabling the watchdog twice in rapdi succession doesn't
> trigger the issue as well. All good.
> 
> Cheers
> Ahmad
> 
> > 
> > Regards,
> >   Marco
> > 
> >> Cheers
> >> Ahmad
> >>
> >>>>>
> >>>>> Signed-off-by: Marco Felsch <m.felsch@pengutronix.de>
> >>>>> ---
> >>>>>  drivers/mfd/da9063.c | 11 +++++++++++
> >>>>>  1 file changed, 11 insertions(+)
> >>>>>
> >>>>> diff --git a/drivers/mfd/da9063.c b/drivers/mfd/da9063.c
> >>>>> index 4d459c7f18..ab57885240 100644
> >>>>> --- a/drivers/mfd/da9063.c
> >>>>> +++ b/drivers/mfd/da9063.c
> >>>>> @@ -14,6 +14,7 @@
> >>>>>   */
> >>>>>  
> >>>>>  #include <common.h>
> >>>>> +#include <clock.h>
> >>>>>  #include <driver.h>
> >>>>>  #include <gpio.h>
> >>>>>  #include <restart.h>
> >>>>> @@ -33,6 +34,7 @@ struct da9063 {
> >>>>>  	struct i2c_client	*client1;
> >>>>>  	struct device_d		*dev;
> >>>>>  	unsigned int		timeout;
> >>>>> +	uint64_t		last_ping;
> >>>>>  };
> >>>>>  
> >>>>>  /* forbidden/impossible value; timeout will be set to this value initially to
> >>>>> @@ -237,6 +239,13 @@ static int da9063_watchdog_ping(struct da9063 *priv)
> >>>>>  	int ret;
> >>>>>  	u8 val;
> >>>>>  
> >>>>> +	/* We need to wait at least 200ms till we can resend a ping */
> >>>>> +	if (!is_timeout_non_interruptible(priv->last_ping, 200 * MSECOND)) {
> >>>>> +		dev_dbg(priv->dev, "active ping delay\n");
> >>>>> +		mdelay(50);
> >>>>
> >>>> I would expect to wait the missing time to 200ms here. Maybe doing
> >>>> nothing in this case would be more appropriate here. I mean, why should
> >>>> you slow down barebox here when some code triggers the watchdog too
> >>>> often?
> >>>>
> >>>>> +		return da9063_watchdog_ping(priv);
> >>>>
> >>>> Drop this, just fall through.
> >>>
> >>> Just prepared a v2 with a busy wait after discussed it with Lucas.
> >>> Thanks for your input too :)
> >>>
> >>> Regards,
> >>>   Marco
> >>>
> >>>> Sascha
> >>>>
> >>>> -- 
> >>>> Pengutronix e.K.                           |                             |
> >>>> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
> >>>> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
> >>>> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
> >>>>
> >>>
> >>
> >> -- 
> >> Pengutronix e.K.                           |                             |
> >> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
> >> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
> >> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
> >>
> > 
> 
> 
> -- 
> Pengutronix e.K.                           |                             |
> Industrial Linux Solutions                 | http://www.pengutronix.de/  |
> Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
> Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |
> 

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |

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