linux-kernel - Re: [PATCH v4 1/5] usb: dwc3: core: Host wake up support from system suspend

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Date:   Thu, 10 Dec 2020 16:04:17 -0800
From:   Matthias Kaehlcke <mka@...omium.org>
To:     mgautam@...eaurora.org
Cc:     Sandeep Maheswaram <sanm@...eaurora.org>,
        Andy Gross <agross@...nel.org>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Felipe Balbi <balbi@...nel.org>,
        Stephen Boyd <swboyd@...omium.org>,
        Doug Anderson <dianders@...omium.org>,
        linux-arm-msm@...r.kernel.org, linux-usb@...r.kernel.org,
        devicetree@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/5] usb: dwc3: core: Host wake up support from system
 suspend

On Sat, Nov 28, 2020 at 08:01:31AM +0530, mgautam@...eaurora.org wrote:
> Hi,
> 
> 
> On 2020-10-28 02:07, Sandeep Maheswaram wrote:
> > Avoiding phy powerdown in host mode so that it can be woken up by
> > devices.
> > Added hs_phy_mode flag to check connection status and set phy mode
> > and configure interrupts.
> > 
> > Signed-off-by: Sandeep Maheswaram <sanm@...eaurora.org>
> > ---
> >  drivers/usb/dwc3/core.c | 14 +++-----------
> >  drivers/usb/dwc3/core.h |  2 ++
> >  2 files changed, 5 insertions(+), 11 deletions(-)
> > 
> > diff --git a/drivers/usb/dwc3/core.c b/drivers/usb/dwc3/core.c
> > index bdf0925..0e4bc1e 100644
> > --- a/drivers/usb/dwc3/core.c
> > +++ b/drivers/usb/dwc3/core.c
> > @@ -1672,10 +1672,6 @@ 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;
> > -		}
> 
> 
> This could be a problem for platforms that don't support runtime_suspend
> and rely on dwc3_core_exit to power-down PHY.
> IMO you can continue to do dwc3_core_exit() if runtime_pm isn't enabled
> for the device.

This would imply that USB wakeup isn't supported on such platforms, right?

Could we have a flag that the dwc3-<glue> driver can set to indicate that
wakeup is enabled for this suspend cycle to omit the PHY power-down?

> > 
> >  		/* Let controller to suspend HSPHY before PHY driver suspends */
> >  		if (dwc->dis_u2_susphy_quirk ||
> > @@ -1733,13 +1729,9 @@ 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)) {
> > -			ret = dwc3_core_init_for_resume(dwc);
> > -			if (ret)
> > -				return ret;
> > -			dwc3_set_prtcap(dwc, DWC3_GCTL_PRTCAP_HOST);
> > -			break;
> > -		}
> > +
> > +		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)
> > diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> > index 74323b1..da63d4a3 100644
> > --- a/drivers/usb/dwc3/core.h
> > +++ b/drivers/usb/dwc3/core.h
> > @@ -1101,6 +1101,8 @@ struct dwc3 {
> > 
> >  	bool			phys_ready;
> > 
> > +	unsigned int            hs_phy_mode;
> > +
> 
> This change should instead be part of the other patch ?
> "usb: dwc3: host: Add suspend_quirk for dwc3 host"

+1