Re: [PATCH v2 3/8] watchdog: JZ4740: Register a restart handler

[Guenter Roeck]

On 01/19/2018 11:31 PM, PrasannaKumar Muralidharan wrote:
> Hi Paul,
>
> On 30 December 2017 at 19:21, Paul Cercueil <paul@xxxxxxxxxxxxxxx> wrote:
> > The watchdog driver can restart the system by simply configuring the
> > hardware for a timeout of 0 seconds.
> >
> > Signed-off-by: Paul Cercueil <paul@xxxxxxxxxxxxxxx>
> > Reviewed-by: Guenter Roeck <linux@xxxxxxxxxxxx>
> > ---
> >   drivers/watchdog/jz4740_wdt.c | 9 +++++++++
> >   1 file changed, 9 insertions(+)
> >
> >   v2: No change
> >
> > diff --git a/drivers/watchdog/jz4740_wdt.c b/drivers/watchdog/jz4740_wdt.c
> > index 92d6ca8ceb49..fa7f49a3212c 100644
> > --- a/drivers/watchdog/jz4740_wdt.c
> > +++ b/drivers/watchdog/jz4740_wdt.c
> > @@ -130,6 +130,14 @@ static int jz4740_wdt_stop(struct watchdog_device *wdt_dev)
> >          return 0;
> >   }
> >
> > +static int jz4740_wdt_restart(struct watchdog_device *wdt_dev,
> > +                             unsigned long action, void *data)
> > +{
> > +       wdt_dev->timeout = 0;
> > +       jz4740_wdt_start(wdt_dev);
> > +       return 0;
> > +}
> > +
> >   static const struct watchdog_info jz4740_wdt_info = {
> >          .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
> >          .identity = "jz4740 Watchdog",
> > @@ -141,6 +149,7 @@ static const struct watchdog_ops jz4740_wdt_ops = {
> >          .stop = jz4740_wdt_stop,
> >          .ping = jz4740_wdt_ping,
> >          .set_timeout = jz4740_wdt_set_timeout,
> > +       .restart = jz4740_wdt_restart,
> >   };
> >
> >   #ifdef CONFIG_OF
> > --
> > 2.11.0
>
> Noticed that min_timeout of the watchdog device is set to 1 but this
> function calls start with timeout set to 0. Even though this works I
> feel it is better to set min_timeout to 0.

No. That would be wrong. If you want to be pedantic, write a new function
__jz4740_wdt_set_timeout(u16 clock_div, u16 timeout_value) and call it
instead, but don't mess with min_timeout.

Guenter