linux-kernel - Re: [PATCH 1/9] arm64: dts: qcom: sc7180: Make watchdog bark interrupt edge triggered

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Message-ID: <20231106223651.GZ3553829@hu-bjorande-lv.qualcomm.com>
Date:   Mon, 6 Nov 2023 14:36:51 -0800
From:   Bjorn Andersson <quic_bjorande@...cinc.com>
To:     Doug Anderson <dianders@...omium.org>
CC:     Stephen Boyd <swboyd@...omium.org>,
        Bjorn Andersson <andersson@...nel.org>,
        Conor Dooley <conor+dt@...nel.org>,
        Guenter Roeck <linux@...ck-us.net>,
        Konrad Dybcio <konrad.dybcio@...aro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        <linux-watchdog@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        Rob Herring <robh+dt@...nel.org>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>,
        Andy Gross <agross@...nel.org>,
        "Guilherme G. Piccoli" <gpiccoli@...lia.com>,
        Kees Cook <keescook@...omium.org>,
        Sai Prakash Ranjan <quic_saipraka@...cinc.com>,
        Tony Luck <tony.luck@...el.com>,
        <cros-qcom-dts-watchers@...omium.org>,
        <devicetree@...r.kernel.org>, <linux-hardening@...r.kernel.org>,
        <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/9] arm64: dts: qcom: sc7180: Make watchdog bark
 interrupt edge triggered

On Mon, Nov 06, 2023 at 01:52:58PM -0800, Doug Anderson wrote:
> Hi,
> 
> On Mon, Nov 6, 2023 at 1:49 PM Stephen Boyd <swboyd@...omium.org> wrote:
> >
> > 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).
> 

I'd be happy to pick your resubmitted series. Thanks for cleaning this
up across the platforms.

Regards,
Bjorn

> 
> > > 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 interrupt")
> > > Signed-off-by: Douglas Anderson <dianders@...omium.org>
> > > ---
> >
> > Reviewed-by: Stephen Boyd <swboyd@...omium.org>
> 
> Thanks!
> 
> -Doug