From: Tzung-Bi Shih <tzungbi@kernel.org>
To: Guenter Roeck <linux@roeck-us.net>
Cc: Wanming Gao <wanming.gao@mediatek.com>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
Matthias Brugger <matthias.bgg@gmail.com>,
AngeloGioacchino Del Regno
<angelogioacchino.delregno@collabora.com>,
linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org,
linux-mediatek@lists.infradead.org, wallace.yu@mediatek.com,
Jarried.Lin@mediatek.com, vince-wl.liu@mediatek.com
Subject: Re: [PATCH v2] watchdog: mediatek: acknowledge pretimeout interrupt
Date: Fri, 28 Aug 2026 02:08:39 +0000 [thread overview]
Message-ID: <apDtp62h_4uZQ84H@google.com> (raw)
In-Reply-To: <5e1793d5-6c78-4372-872a-069fcd99a07a@roeck-us.net>
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>
next prev parent reply other threads:[~2026-08-28 2:08 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-08-27 9:26 [PATCH v2] watchdog: mediatek: acknowledge pretimeout interrupt Wanming Gao
2026-08-27 13:54 ` Guenter Roeck
2026-08-28 2:08 ` Tzung-Bi Shih [this message]
2026-08-28 3:08 ` Guenter Roeck
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