linux-kernel - Re: [PATCH v18 2/5] usb: dwc3: core: Host wake up support from system suspend

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Date:   Thu, 26 May 2022 08:13:19 +0530
From:   Pavan Kondeti <quic_pkondeti@...cinc.com>
To:     Krishna Kurapati <quic_kriskura@...cinc.com>
CC:     Krzysztof Kozlowski <krzysztof.kozlowski+dt@...aro.org>,
        Rob Herring <robh+dt@...nel.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Felipe Balbi <balbi@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Doug Anderson <dianders@...omium.org>,
        "Matthias Kaehlcke" <mka@...omium.org>,
        Mathias Nyman <mathias.nyman@...el.com>,
        <devicetree@...r.kernel.org>, <linux-arm-msm@...r.kernel.org>,
        <linux-usb@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        <linux-pm@...r.kernel.org>, <quic_pkondeti@...cinc.com>,
        <quic_ppratap@...cinc.com>, <quic_vpulyala@...cinc.com>,
        Sandeep Maheswaram <quic_c_sanm@...cinc.com>
Subject: Re: [PATCH v18 2/5] usb: dwc3: core: Host wake up support from
 system suspend

On Wed, May 25, 2022 at 11:50:23PM +0530, Krishna Kurapati wrote:
> From: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
> 
> Check wakeup-source property for dwc3 core node to set the
> wakeup capability. Drop the device_init_wakeup call from
> runtime suspend and resume.
> 
> If the dwc3 is wakeup capable, don't power down the USB PHY(s).
> The glue drivers are expected to take care of configuring the
> additional wakeup settings if needed based on the dwc3 wakeup
> capability status. In some SOC designs, powering off the PHY is
> resulting in higher leakage, so this patch save power on such boards.
> 
> Signed-off-by: Sandeep Maheswaram <quic_c_sanm@...cinc.com>
> Signed-off-by: Krishna Kurapati <quic_kriskura@...cinc.com>
> Reviewed-by: Pavankumar Kondeti <quic_pkondeti@...cinc.com>
> Reviewed-by: Matthias Kaehlcke <mka@...omium.org>
> ---
>  drivers/usb/dwc3/core.c | 26 ++++++++++++--------------
>  1 file changed, 12 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index e027c04..2b1b3f7 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1787,6 +1787,7 @@ static int dwc3_probe(struct platform_device *pdev)
>  
>  	platform_set_drvdata(pdev, dwc);
>  	dwc3_cache_hwparams(dwc);
> +	device_init_wakeup(&pdev->dev, of_property_read_bool(dev->of_node, "wakeup-source"));
>  
>  	spin_lock_init(&dwc->lock);
>  	mutex_init(&dwc->mutex);
> @@ -1948,11 +1949,6 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>  		dwc3_core_exit(dwc);
>  		break;
>  	case DWC3_GCTL_PRTCAP_HOST:
> -		if (!PMSG_IS_AUTO(msg)) {
> -			dwc3_core_exit(dwc);
> -			break;
> -		}
> -
>  		/* Let controller to suspend HSPHY before PHY driver suspends */
>  		if (dwc->dis_u2_susphy_quirk ||
>  		    dwc->dis_enblslpm_quirk) {
> @@ -1967,6 +1963,11 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
>  
>  		phy_pm_runtime_put_sync(dwc->usb2_generic_phy);
>  		phy_pm_runtime_put_sync(dwc->usb3_generic_phy);
> +
> +		if (!PMSG_IS_AUTO(msg)) {
> +			if (!device_can_wakeup(dwc->dev))
> +				dwc3_core_exit(dwc);
> +		}
>  		break;

Earlier, the dwc3 which does not support wakeup just calls dwc3_core_exit().
With this patch we are modifying the behavior. Is that intentional? I expect
it to be something like

@@ -1761,8 +1782,10 @@ static int dwc3_suspend_common(struct dwc3 *dwc, pm_message_t msg)
                break;
        case DWC3_GCTL_PRTCAP_HOST:
                if (!PMSG_IS_AUTO(msg)) {
-                       dwc3_core_exit(dwc);
-                       break;
+                       if (!device_can_wakeup(dwc->dev)) {
+                               dwc3_core_exit(dwc);
+                               break;
+                       }
                }

                /* Let controller to suspend HSPHY before PHY driver suspends */

Thanks,
Pavan