linux-kernel - Re: [PATCH 3/3] usb: dwc3-am62: Fix up wake-up configuration and spurious wake up

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Date:   Thu, 23 Mar 2023 19:18:26 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Roger Quadros <rogerq@...nel.org>
Cc:     Thinh.Nguyen@...opsys.com, stern@...land.harvard.edu,
        vigneshr@...com, srk@...com, r-gunasekaran@...com,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] usb: dwc3-am62: Fix up wake-up configuration and
 spurious wake up

On Mon, Mar 20, 2023 at 10:24:17AM +0200, Roger Quadros wrote:
> Hi,
> 
> On 16/03/2023 15:12, Roger Quadros wrote:
> > Explicitly set and clear wakeup config so we don't leave anything
> > to chance.
> > 
> > Clear wakeup status on suspend so we know what caused wake up.
> > 
> > The LINESTATE wake up should not be enabled in device mode
> > if we are not connected to a USB host else it will cause spurious
> > wake up.
> > 
> > Signed-off-by: Roger Quadros <rogerq@...nel.org>
> > ---
> >  drivers/usb/dwc3/dwc3-am62.c | 32 ++++++++++++++++++++++----------
> >  1 file changed, 22 insertions(+), 10 deletions(-)
> > 
> > diff --git a/drivers/usb/dwc3/dwc3-am62.c b/drivers/usb/dwc3/dwc3-am62.c
> > index 859b48279658..af0524e2f1e1 100644
> > --- a/drivers/usb/dwc3/dwc3-am62.c
> > +++ b/drivers/usb/dwc3/dwc3-am62.c
> > @@ -60,6 +60,13 @@
> >  #define USBSS_WAKEUP_CFG_SESSVALID_EN	BIT(1)
> >  #define USBSS_WAKEUP_CFG_VBUSVALID_EN	BIT(0)
> >  
> > +#define USBSS_WAKEUP_CFG_ALL	(USBSS_WAKEUP_CFG_VBUSVALID_EN | \
> > +				 USBSS_WAKEUP_CFG_SESSVALID_EN | \
> > +				 USBSS_WAKEUP_CFG_LINESTATE_EN | \
> > +				 USBSS_WAKEUP_CFG_OVERCURRENT_EN)
> > +
> > +#define USBSS_WAKEUP_CFG_NONE	0
> > +
> >  /* WAKEUP STAT register bits */
> >  #define USBSS_WAKEUP_STAT_OVERCURRENT	BIT(4)
> >  #define USBSS_WAKEUP_STAT_LINESTATE	BIT(3)
> > @@ -103,6 +110,7 @@ struct dwc3_data {
> >  	struct regmap *syscon;
> >  	unsigned int offset;
> >  	unsigned int vbus_divider;
> > +	u32 wakeup_stat;
> >  };
> >  
> >  static const int dwc3_ti_rate_table[] = {	/* in KHZ */
> > @@ -294,6 +302,7 @@ static int dwc3_ti_suspend_common(struct device *dev)
> >  {
> >  	struct dwc3_data *data = dev_get_drvdata(dev);
> >  	u32 reg, current_prtcap_dir;
> > +	u32 vbus_stat;
> >  
> >  	if (device_may_wakeup(dev)) {
> >  		reg = dwc3_ti_readl(data, USBSS_CORE_STAT);
> > @@ -302,12 +311,20 @@ static int dwc3_ti_suspend_common(struct device *dev)
> >  		/* Set wakeup config enable bits */
> >  		reg = dwc3_ti_readl(data, USBSS_WAKEUP_CONFIG);
> >  		if (current_prtcap_dir == DWC3_GCTL_PRTCAP_HOST) {
> > -			reg |= USBSS_WAKEUP_CFG_LINESTATE_EN | USBSS_WAKEUP_CFG_OVERCURRENT_EN;
> > +			reg = USBSS_WAKEUP_CFG_LINESTATE_EN | USBSS_WAKEUP_CFG_OVERCURRENT_EN;
> >  		} else {
> > -			reg |= USBSS_WAKEUP_CFG_OVERCURRENT_EN | USBSS_WAKEUP_CFG_LINESTATE_EN |
> > -			       USBSS_WAKEUP_CFG_VBUSVALID_EN;
> > +			reg = USBSS_WAKEUP_CFG_VBUSVALID_EN | USBSS_WAKEUP_CFG_SESSVALID_EN;
> > +			/*
> > +			 * Enable LINESTATE wake up only if connected to bus else
> > +			 * it causes spurious wake-up.
> > +			 */
> > +			vbus_stat = dwc3_ti_readl(data, USBSS_VBUS_STAT);
> > +			if (vbus_stat & (USBSS_VBUS_STAT_SESSVALID | USBSS_VBUS_STAT_VBUSVALID))
> > +				reg |= USBSS_WAKEUP_CFG_LINESTATE_EN;
> 
> There is one corner case where a spurious wake-up still happens.
> i.e. If we are not in USB_SUSPEND state while entering SoC sleep.
> 
> So looks like we need to check if we are in USB SUSPEND before enabling
> LINESTATE wakeup enable.

Ok, I'll not apply this one, only the first 2 now.

thanks,

greg k-h