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From:   Doug Anderson <dianders@chromium.org>
Date:   Mon, 6 Nov 2023 13:52:58 -0800
Message-ID: <CAD=FV=UJE6VKrjFJ2g=4qRHLdnqymossWSAFeKyUykxm1sTCtQ@mail.gmail.com>
Subject: Re: [PATCH 1/9] arm64: dts: qcom: sc7180: Make watchdog bark
 interrupt edge triggered
To:     Stephen Boyd <swboyd@chromium.org>
Cc:     Bjorn Andersson <andersson@kernel.org>,
        Conor Dooley <conor+dt@kernel.org>,
        Guenter Roeck <linux@roeck-us.net>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        linux-watchdog@vger.kernel.org, linux-arm-msm@vger.kernel.org,
        Rob Herring <robh+dt@kernel.org>,
        Wim Van Sebroeck <wim@linux-watchdog.org>,
        Andy Gross <agross@kernel.org>,
        "Guilherme G. Piccoli" <gpiccoli@igalia.com>,
        Kees Cook <keescook@chromium.org>,
        Sai Prakash Ranjan <quic_saipraka@quicinc.com>,
        Tony Luck <tony.luck@intel.com>,
        cros-qcom-dts-watchers@chromium.org, devicetree@vger.kernel.org,
        linux-hardening@vger.kernel.org, linux-kernel@vger.kernel.org
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Hi,

On Mon, Nov 6, 2023 at 1:49=E2=80=AFPM Stephen Boyd <swboyd@chromium.org> w=
rote:
>
> Quoting Douglas Anderson (2023-11-03 16:34:27)
> > On sc7180 when the watchdog timer fires your logs get filled with:
> >   watchdog0: pretimeout event
> >   watchdog0: pretimeout event
> >   watchdog0: pretimeout event
> >   ...
> >   watchdog0: pretimeout event
> >
> > If you're using console-ramoops to debug crashes the above gets quite
> > annoying since it blows away any other log messages that might have
> > been there.
> >
> > The issue is that the "bark" interrupt (AKA the "pretimeout"
> > interrupt) remains high until the watchdog is pet. Since we've got
> > things configured as "level" triggered we'll keep getting interrupted
> > over and over.
> >
> > Let's switch to edge triggered. Now we'll get one interrupt when the
> > "bark" interrupt goes off we'll get one interrupt and won't get
>
> "We'll get one" twice?

I like to make like to make typos. If you hadn't hadn't noticed.

I'll wait another few days and send a version with the typo fixed
unless Bjorn tells me not to (because he didn't care and applied it
anyway or because he fixed it himself while applying).


> > another one until the "bark" interrupt is cleared and asserts again.
> >
> > This matches how many older Qualcomm SoCs have things configured.
> >
> > Fixes: 28cc13e4060c ("arm64: dts: qcom: sc7180: Add watchdog bark inter=
rupt")
> > Signed-off-by: Douglas Anderson <dianders@chromium.org>
> > ---
>
> Reviewed-by: Stephen Boyd <swboyd@chromium.org>

Thanks!

-Doug