Re: [PATCH v2 2/3] watchdog: sama5d4: Fix setting timeout when watchdog is disabled

From: Alexandre Belloni
Date: Fri Feb 17 2017 - 10:16:57 EST


On 17/02/2017 at 06:40:33 -0800, Guenter Roeck wrote:
> On 02/16/2017 11:30 AM, Alexandre Belloni wrote:
> > The datasheet states: "When setting the WDDIS bit, and while it is set, the
> > fields WDV and WDD must not be modified."
> >
> > Ensure WDDIS is not set when changing the timeout and set it afterwards if
> > the watchdog was disabled.
> >
> > Signed-off-by: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
> > ---
> > Changes in v2:
> > - new patch
> > drivers/watchdog/sama5d4_wdt.c | 9 ++++++++-
> > 1 file changed, 8 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
> > index 2c6f5a70ae67..2a60251806d2 100644
> > --- a/drivers/watchdog/sama5d4_wdt.c
> > +++ b/drivers/watchdog/sama5d4_wdt.c
> > @@ -90,11 +90,18 @@ static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
> > u32 reg;
> >
> > reg = wdt_read(wdt, AT91_WDT_MR);
> > +
> > + if (reg & AT91_WDT_WDDIS)
> > + wdt_write(wdt, AT91_WDT_MR, reg & ~AT91_WDT_WDDIS);
> > +
> > reg &= ~AT91_WDT_WDV;
> > reg &= ~AT91_WDT_WDD;
> > reg |= AT91_WDT_SET_WDV(value);
> > reg |= AT91_WDT_SET_WDD(value);
> > - wdt_write(wdt, AT91_WDT_MR, reg);
> > + wdt_write(wdt, AT91_WDT_MR, reg & ~AT91_WDT_WDDIS);
> > +
> > + if (reg & AT91_WDT_WDDIS)
> > + wdt_write(wdt, AT91_WDT_MR, reg);
> >
> That means if the watchdog is running, the timeout would not be updated.
> It should be updated no matter if it is running or not.
>

No, it is enabling the watchdog, then changing WDV and WDD and finally
disabling the watchdog if necessary. So, WDV and WDD are always changed.

--
Alexandre Belloni, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com