Re: [PATCH 0/4] Add support for Kernel WDT

[Jon Hunter]

On 07/05/2026 16:45, Kartik Rajput wrote:
> Tegra186 and later SoCs support multiple watchdog timers in the TKE
> block, the driver so far only uses WDT0. This series extends it to
> make use of the additional instances and reserve the first available WDT
> for Kernel.
>
> Patch 1 fixes a read-modify-write bug in tegra186_wdt_enable()
> that would otherwise make registering more than one watchdog unsafe.
>
> Patch 2 corrects num_wdts for Tegra186 and Tegra234. WDT2 is connected
> to the Audio Processing Engine (APE) and cannot be accessed from Linux,
> so only WDT0 and WDT1 are available.
>
> Patch 3 iterates over all WDTs and registers the ones whose TKE SCR
> firewall grants OS access.
>
> Patch 4 reserves the first accessible watchdog as a kernel-only
> watchdog, arms it at probe with a 120 s timeout, and pets it from
> the driver's IRQ handler, it is not exposed to userspace, so the
> system can still reset if the kernel hangs before userspace opens a
> watchdog.
>
> Kartik Rajput (4):
>    clocksource/drivers/timer-tegra186: Fix support for multiple watchdog
>      instances
>    clocksource/drivers/timer-tegra186: Correct num_wdts for Tegra186 and
>      Tegra234
>    clocksource/drivers/timer-tegra186: Register all accessible watchdog
>      timers
>    clocksource/drivers/timer-tegra186: Reserve and service a kernel
>      watchdog
>
>   drivers/clocksource/timer-tegra186.c | 122 +++++++++++++++++++++++----
>   1 file changed, 104 insertions(+), 18 deletions(-)

For the series ...

Reviewed-by: Jon Hunter <jonathanh@xxxxxxxxxx>

Thanks!
Jon

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