[PATCH] watchdog: Fix watchdog enablement in SPL and TPL

[Marcel Ziswiler]

On Tue, 2021-08-31 at 11:17 +0200, Marek Vasut wrote:
> On 8/31/21 8:49 AM, Marcel Ziswiler wrote:
> > Hi Marek
> > 
> > On Tue, 2021-08-31 at 00:03 +0200, Marek Vasut wrote:
> > > Commit 830d29ac372 ("watchdog: Allow to use CONFIG_WDT without starting watchdog")
> > > completely broke WDT operation in both SPL and TPL, in either case those
> > > WDTs are never enabled. Fix it by filling in the missing Kconfig options
> > > for SPL and TPL.
> > > 
> > > Fixes: 830d29ac372 ("watchdog: Allow to use CONFIG_WDT without starting watchdog")
> > > Signed-off-by: Marek Vasut <marex at denx.de>
> > > Cc: Pali Rohar <pali at kernel.org>
> > > Cc: Stefan Roese <sr at denx.de>
> > > ---
> > >   drivers/watchdog/Kconfig | 20 ++++++++++++++++++++
> > >   1 file changed, 20 insertions(+)
> > > 
> > > diff --git a/drivers/watchdog/Kconfig b/drivers/watchdog/Kconfig
> > > index f0ff2612a6b..65d974c4dd5 100644
> > > --- a/drivers/watchdog/Kconfig
> > > +++ b/drivers/watchdog/Kconfig
> > > @@ -273,4 +273,24 @@ config SPL_WDT
> > >            Enable driver model for watchdog timer in SPL.
> > >            This is similar to CONFIG_WDT in U-Boot.
> > >   
> > > +config SPL_WATCHDOG_AUTOSTART
> > > +       bool "Automatically start watchdog timer in SPL"
> > > +       depends on SPL && WDT
> > > +       default y
> > > +       help
> > > +         Automatically start watchdog timer and start servicing it during
> > > +         SPL phase. Enabled by default. Disable this option if you want
> > > +         to compile U-Boot with CONFIG_WDT support but do not want to
> > > +         activate watchdog, like when CONFIG_WDT option is disabled.
> > > +
> > > +config TPL_WATCHDOG_AUTOSTART
> > > +       bool "Automatically start watchdog timer in TPL"
> > > +       depends on TPL && WDT
> > > +       default y
> > > +       help
> > > +         Automatically start watchdog timer and start servicing it during
> > > +         TPL phase. Enabled by default. Disable this option if you want
> > > +         to compile U-Boot with CONFIG_WDT support but do not want to
> > > +         activate watchdog, like when CONFIG_WDT option is disabled.
> > > +
> > >   endmenu
> > 
> > Those Kconfig entries look fine. However, I am wondering where exactly they get used. Am I missing
> > anything?
> 
> Have a look at the patch this Fixes:, if those Kconfig entries are not 
> present, the WDT is disabled in SPL and TPL unconditionally.

Yes, I did. But I guess I was not aware of how exactly that CONFIG_IS_ENABLED(WATCHDOG_AUTOSTART) behaves.
While I have not really found this documented or the implementation thereof I assume it pre-fixes config stuff
with SPL_ resp. TPL_ when building those flavors, correct?

I am wondering how many others are unaware of this (just like the author of the patch this fixes). Maybe we
should at least document this properly somewhere, not?

> It could be that if you're using some non-free or proprietary preloader 
> instead of SPL, you won't run into this problem.

No, don't worry. I am not running anything evil (;-p).