linux-kernel - Re: [PATCH 2/8] Revert "usb: dwc3: qcom: Keep power domain on to retain controller status"

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Message-ID: <Yuom7k3Y4tDhy/QJ@hovoldconsulting.com>
Date:   Wed, 3 Aug 2022 09:42:38 +0200
From:   Johan Hovold <johan@...nel.org>
To:     Krishna Kurapati PSSNV <quic_kriskura@...cinc.com>
Cc:     Johan Hovold <johan+linaro@...nel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Felipe Balbi <balbi@...nel.org>,
        Rob Herring <robh+dt@...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>,
        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@...r.kernel.org, linux-usb@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/8] Revert "usb: dwc3: qcom: Keep power domain on to
 retain controller status"

On Tue, Aug 02, 2022 at 11:30:34PM +0530, Krishna Kurapati PSSNV wrote:
> 
> On 8/2/2022 8:43 PM, Johan Hovold wrote:
> > This reverts commit d9be8d5c5b032e5383ff5c404ff4155e9c705429.
> >
> > Generic power-domain flags must be set before the power-domain is
> > initialised and must specifically not be modified by drivers for devices
> > that happen to be in the domain.
> >
> > To make sure that USB power-domains are left enabled during system
> > suspend when a device in the domain is in the wakeup path, the
> > GENPD_FLAG_ACTIVE_WAKEUP flag should instead be set for the domain
> > unconditionally when it is registered.

> In case we need the genpd framework to set the GENPD_FLAG_ACTIVE_WAKEUP
> flag for a particular domain that will be used by a device (which is
> wakeup capable) and hasn't been probed yet , can you help me understand if
> there any dt-flags we  can add to convey the same the genpd  framework
> so that it will set that flag during domain registration ?

This can't be expressed in DT (currently), so what you need is something
like the below:

diff --git a/drivers/clk/qcom/gcc-sc7280.c b/drivers/clk/qcom/gcc-sc7280.c
index 7ff64d4d5920..4ff855269467 100644
--- a/drivers/clk/qcom/gcc-sc7280.c
+++ b/drivers/clk/qcom/gcc-sc7280.c
@@ -3125,6 +3125,7 @@ static struct gdsc gcc_usb30_prim_gdsc = {
        .gdscr = 0xf004,
        .pd = {
                .name = "gcc_usb30_prim_gdsc",
+               .flags = GENPD_FLAG_ACTIVE_WAKEUP,
        },
        .pwrsts = PWRSTS_OFF_ON,
        .flags = VOTABLE,
@@ -3134,6 +3135,7 @@ static struct gdsc gcc_usb30_sec_gdsc = {
        .gdscr = 0x9e004,
        .pd = {
                .name = "gcc_usb30_sec_gdsc",
+               .flags = GENPD_FLAG_ACTIVE_WAKEUP,
        },
        .pwrsts = PWRSTS_OFF_ON,
        .flags = VOTABLE,

to make sure that genpd keeps these domains powered during system
suspend if they are used by devices that are in the wakeup path.

Johan