Re: [PATCH v2] watchdog: mediatek: acknowledge pretimeout interrupt

[Tzung-Bi Shih <tzungbi@kernel.org>]

On Thu, Aug 27, 2026 at 06:54:03AM -0700, Guenter Roeck wrote:
> On Thu, Aug 27, 2026 at 05:26:12PM +0800, Wanming Gao wrote:
> > The MediaTek watchdog pretimeout interrupt is level-triggered and does
> > not have a separate acknowledge register. The interrupt is cleared by
> > changing WDT_MODE_IRQ_LEVEL_EN and then restoring it to its original
> > state. Without this transition, the interrupt may remain asserted and
> > cause an interrupt storm.
> > 
> > After changing WDT_MODE_IRQ_LEVEL_EN, wait 70 us before restoring it.
> > This is longer than two 32 kHz watchdog clock cycles, allowing the
> > level change to propagate across the clock domain.
> > 
> > WDT_MODE is also updated by the watchdog start, stop, and pretimeout
> > operations. Protect its read-modify-write sequences and the complete
> > IRQ acknowledge sequence with the watchdog spinlock so that concurrent
> > updates cannot overwrite the temporary IRQ level state.
> > 
> > Signed-off-by: Wanming Gao <wanming.gao@mediatek.com>
> 
> Applied.

Might be a bit late, but tested on a MT8196 board:
Tested-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>