[PATCH 1/2] timer: tegra: Bind watchdog driver when timer node is processed

[Tom Rini]

On Tue, Sep 09, 2025 at 02:26:19PM +0300, Svyatoslav Ryhel wrote:
> вт, 9 вер. 2025 р. о 13:15 Łukasz Majewski <lukma at nabladev.com> пише:
> >
> > Hi Svyatoslav,
> >
> > > пн, 8 вер. 2025 р. о 15:41 Łukasz Majewski <lukma at nabladev.com> пише:
> > > >
> > > > Hi Svyatoslav,
> > > >
> > > > > вт, 26 серп. 2025 р. о 12:39 Lukasz Majewski <lukma at nabladev.com>
> > > > > пише:
> > > > > >
> > > > > > The Tegra30 SoC is a bit special, as it doesn't have the
> > > > > > separate IP block to provide watchdog functionality.
> > > > > >
> > > > > > Instead, timer IP block allows such functionality when properly
> > > > > > configured.
> > > > > >
> > > > > > As in the tegra30.dtsi there is a timer node, which "covers" all
> > > > > > timers, with 'nvidia,tegra30-timer' compatibility it was
> > > > > > necessary to manually bind U-Boot's WDT driver (based on
> > > > > > WDT_UCLASS).
> > > > > >
> > > > > > Signed-off-by: Lukasz Majewski <lukma at nabladev.com>
> > > > > > ---
> > > > > >  drivers/timer/tegra-timer.c | 18 ++++++++++++++++++
> > > > > >  1 file changed, 18 insertions(+)
> > > > > >
> > > > >
> > > > > What is the practical application for this diver in therms of
> > > > > Tegra and U-Boot overall?
> > > >
> > > > You have the WDT functionality working. It uses the same DTS
> > > > bindings as ones used in Linux.
> > >
> > > Why do we need WDT for Tegra in U-Boot at all?
> >
> > Can you correct me if I draw wrong conclusion - you ask why Tegra needs
> > to support watchdog in u-boot bootloader ?
> >
> > > It is not used and has
> > > no practical application.
> > >
> >
> > Yes, it has ...
> >
> > Customer has number of Tegra30 colibri modules in the field. They want
> > to switch to u-boot + linux kernel BSP.
> >
> > For their application - it would be welcome if the device could reboot
> > and start emergency procedure in the case of not being able to start
> > Linux.
> >
> > The procedure is that we start Watchdog at very early boot - then we do
> > have for example 30 seconds to "feed" the Watchdog in Linux
> >
> > When we fail, after watchdog reboot, we can switch to another rootfs
> > partition (the A/B scheme of booting) or start emergency system.
> >
> 
> So when are you going to submit this board variant? If driver has no
> users, it is removed.

I assume it would be enabled on colibri_t30_defconfig.

-- 
Tom
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