linux-kernel - Re: [PATCH v9 2/5] usb: dwc3: core: Host wake up support from system suspend

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Message-ID: <YZRMoNEZTy8XimIx@google.com>
Date:   Tue, 16 Nov 2021 16:28:16 -0800
From:   Brian Norris <briannorris@...omium.org>
To:     Sandeep Maheswaram <quic_c_sanm@...cinc.com>
Cc:     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>,
        linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
        linux-kernel@...r.kernel.org, quic_pkondeti@...cinc.com,
        quic_ppratap@...cinc.com
Subject: Re: [PATCH v9 2/5] usb: dwc3: core: Host wake up support from system
 suspend

On Mon, Nov 01, 2021 at 01:23:41PM +0530, Sandeep Maheswaram wrote:
> Avoiding phy powerdown when wakeup capable devices are connected
> by checking wakeup property of xhci plat device.
> Phy should be on to wake up the device from suspend using wakeup capable
> devices such as keyboard and mouse.
> 
> Signed-off-by: Sandeep Maheswaram <quic_c_sanm@...cinc.com>

Because you've now factored in a device_may_wakeup() (which evaluates
'false' for me), this no longer breaks my Rockchip RK3399 systems
(previous versions did). So from that angle:

Tested-by: Brian Norris <briannorris@...omium.org>

> ---
>  drivers/usb/dwc3/core.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> index 643239d..a6ad0ed 100644
> --- a/drivers/usb/dwc3/core.c
> +++ b/drivers/usb/dwc3/core.c
> @@ -1787,7 +1787,7 @@ 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)) {
> +		if (!PMSG_IS_AUTO(msg) && !device_may_wakeup(&dwc->xhci->dev)) {

I still find it odd to use device_may_wakeup(), since that's something
controlled by user space (sysfs) and doesn't fully factor in hardware
support. But that's what xhci-plat.c is doing, so I guess I see why
you're imitating it...
...still, feels wrong to me. But so does a lot of how dwc3 works.

Brian

>  			dwc3_core_exit(dwc);
>  			break;
>  		}
> @@ -1848,13 +1848,16 @@ static int dwc3_resume_common(struct dwc3 *dwc, pm_message_t msg)
>  		spin_unlock_irqrestore(&dwc->lock, flags);
>  		break;
>  	case DWC3_GCTL_PRTCAP_HOST:
> -		if (!PMSG_IS_AUTO(msg)) {
> +		if (!PMSG_IS_AUTO(msg) && !device_may_wakeup(&dwc->xhci->dev)) {
>  			ret = dwc3_core_init_for_resume(dwc);
>  			if (ret)
>  				return ret;
>  			dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_HOST);
>  			break;
> +		} else {
> +			dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_HOST);
>  		}
> +
>  		/* Restore GUSB2PHYCFG bits that were modified in suspend */
>  		reg = dwc3_readl(dwc->regs, DWC3_GUSB2PHYCFG(0));
>  		if (dwc->dis_u2_susphy_quirk)
> -- 
> 2.7.4
>