linux-kernel - Re: [PATCH v2 1/5] dt-bindings: firmware: qcom,scm: Document SDI disable

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Date:   Mon, 21 Aug 2023 14:31:52 -0500
From:   Rob Herring <robh@...nel.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        Robert Marko <robimarko@...il.com>
Cc:     agross@...nel.org, andersson@...nel.org, konrad.dybcio@...aro.org,
        krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org,
        quic_gurus@...cinc.com, linux-arm-msm@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org,
        computersforpeace@...il.com
Subject: Re: [PATCH v2 1/5] dt-bindings: firmware: qcom,scm: Document SDI
 disable

On Wed, Aug 16, 2023 at 08:15:54AM +0200, Krzysztof Kozlowski wrote:
> On 15/08/2023 15:59, Robert Marko wrote:
> > IPQ5018 has SDI (Secure Debug Image) enabled by TZ by default, and that
> > means that WDT being asserted or just trying to reboot will hang the board
> > in the debug mode and only pulling the power and repowering will help.
> > Some IPQ4019 boards like Google WiFI have it enabled as well.
> > 
> > So, lets add a boolean property to indicate that SDI should be disabled.
> > 
> > Signed-off-by: Robert Marko <robimarko@...il.com>
> > ---
> >  Documentation/devicetree/bindings/firmware/qcom,scm.yaml | 8 ++++++++
> >  1 file changed, 8 insertions(+)
> > 
> > diff --git a/Documentation/devicetree/bindings/firmware/qcom,scm.yaml b/Documentation/devicetree/bindings/firmware/qcom,scm.yaml
> > index 4233ea839bfc..bf753192498a 100644
> > --- a/Documentation/devicetree/bindings/firmware/qcom,scm.yaml
> > +++ b/Documentation/devicetree/bindings/firmware/qcom,scm.yaml
> > @@ -89,6 +89,14 @@ properties:
> >        protocol to handle sleeping SCM calls.
> >      maxItems: 1
> >  
> > +  qcom,sdi-disable:
> 
> The property should describe rather current hardware/firmware state,
> instead of expressing your intention for OS what to do. Therefore rather:
> qcom,sdi-enabled
> or
> qcom,secure-debug-image

Why can't you just disable SDI unconditionally when going into debug 
mode? Is doing that when not enabled going to crash the system or 
something?

Rob