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Sender: Guenter Roeck <groeck7@gmail.com>
Date:   Fri, 3 Nov 2023 17:42:12 -0700
From:   Guenter Roeck <linux@roeck-us.net>
To:     Douglas Anderson <dianders@chromium.org>
Cc:     Bjorn Andersson <andersson@kernel.org>,
        Konrad Dybcio <konrad.dybcio@linaro.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
        Conor Dooley <conor+dt@kernel.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>,
        swboyd@chromium.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
Subject: Re: [PATCH 1/9] arm64: dts: qcom: sc7180: Make watchdog bark
 interrupt edge triggered
Message-ID: <ae5f5cd1-504a-4ed9-9608-b448b83b23cd@roeck-us.net>
References: <20231103163434.1.Ic7577567baff921347d423b722de8b857602efb1@changeid>
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On Fri, Nov 03, 2023 at 04:34:27PM -0700, Douglas Anderson wrote:
> 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
> 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@chromium.org>

Reviewed-by: Guenter Roeck <linux@roeck-us.net>

> ---
> 
>  arch/arm64/boot/dts/qcom/sc7180.dtsi | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/arm64/boot/dts/qcom/sc7180.dtsi b/arch/arm64/boot/dts/qcom/sc7180.dtsi
> index 11f353d416b4..c0365832c315 100644
> --- a/arch/arm64/boot/dts/qcom/sc7180.dtsi
> +++ b/arch/arm64/boot/dts/qcom/sc7180.dtsi
> @@ -3576,7 +3576,7 @@ watchdog@17c10000 {
>  			compatible = "qcom,apss-wdt-sc7180", "qcom,kpss-wdt";
>  			reg = <0 0x17c10000 0 0x1000>;
>  			clocks = <&sleep_clk>;
> -			interrupts = <GIC_SPI 0 IRQ_TYPE_LEVEL_HIGH>;
> +			interrupts = <GIC_SPI 0 IRQ_TYPE_EDGE_RISING>;
>  		};
>  
>  		timer@17c20000 {
> -- 
> 2.42.0.869.gea05f2083d-goog
>