linux-kernel - Re: [PATCH 5/8] Revert "dt-bindings: usb: dwc3: Add wakeup-source property support"

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Message-ID: <CAL_JsqL5ZCzfd06rxOdQodFjk4G3QpDCsxA5heM71x0q5d-hCw@mail.gmail.com>
Date:   Tue, 2 Aug 2022 11:17:22 -0600
From:   Rob Herring <robh+dt@...nel.org>
To:     Johan Hovold <johan+linaro@...nel.org>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Felipe Balbi <balbi@...nel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Manivannan Sadhasivam <manivannan.sadhasivam@...aro.org>,
        Konrad Dybcio <konrad.dybcio@...ainline.org>,
        Krishna Kurapati <quic_kriskura@...cinc.com>,
        Stephen Boyd <swboyd@...omium.org>,
        Doug Anderson <dianders@...omium.org>,
        Matthias Kaehlcke <mka@...omium.org>,
        Pavankumar Kondeti <quic_pkondeti@...cinc.com>,
        quic_ppratap@...cinc.com, quic_vpulyala@...cinc.com,
        linux-arm-msm <linux-arm-msm@...r.kernel.org>,
        Linux USB List <linux-usb@...r.kernel.org>,
        devicetree@...r.kernel.org,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 5/8] Revert "dt-bindings: usb: dwc3: Add wakeup-source
 property support"

On Tue, Aug 2, 2022 at 9:14 AM Johan Hovold <johan+linaro@...nel.org> wrote:
>
> This reverts commit 098c4d43b91a269e89f60331a26a3f3b914677ed.
>
> A devicetree binding should describe hardware capabilities and not be
> used to configure power-management policies (even if things are a bit
> blurry when it comes to "wakeup-source").

Whether a device's interrupt can cause a wakeup is a h/w feature.
That's not policy. If Linux also uses this to decide whether or not to
enable wakeup, then that's its policy.

> It should also not be used to
> work around Linux driver implementation issues such as how to coordinate
> the glue and core dwc3 drivers.
>
> For the Qualcomm dwc3 controllers, it is the glue device that manages
> the wakeup interrupts, which may or may not be able to wake the system
> up from system suspend.

While the reasoning to add this may have been for QCom, having this
property for other users makes sense. On some platforms, 'snps,dwc3'
is the only node (i.e. there's no wrapper node). So I don't think this
should be reverted.

Rob