Re: [PATCH v4 2/5] usb: dwc3: Add remote wakeup handling

[Elson Serrao <quic_eserrao@xxxxxxxxxxx>]

On 2/14/2023 5:09 PM, Thinh Nguyen wrote:
> On Mon, Feb 13, 2023, Elson Roy Serrao wrote:
> > An usb device can initate a remote wakeup and bring the link out of
> > suspend as dictated by the DEVICE_REMOTE_WAKEUP feature selector.
> > Add support to handle this packet and set the remote wakeup capability.
> >
> > Some hosts may take longer time to initiate the resume signaling after
> > device triggers a remote wakeup. So add async support to the wakeup API
> > by enabling link status change events.
> >
> > Signed-off-by: Elson Roy Serrao <quic_eserrao@xxxxxxxxxxx>
> > ---
> >   drivers/usb/dwc3/core.h   |  2 ++
> >   drivers/usb/dwc3/ep0.c    |  4 +++
> >   drivers/usb/dwc3/gadget.c | 74 +++++++++++++++++++++++++++++++++++++++++++----
> >   3 files changed, 74 insertions(+), 6 deletions(-)
> >
> > diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
> > index 582ebd9..cc78236 100644
> > --- a/drivers/usb/dwc3/core.h
> > +++ b/drivers/usb/dwc3/core.h
> > @@ -1110,6 +1110,7 @@ struct dwc3_scratchpad_array {
> >    *	3	- Reserved
> >    * @dis_metastability_quirk: set to disable metastability quirk.
> >    * @dis_split_quirk: set to disable split boundary.
> > + * @wakeup_configured: set if the device is configured for remote wakeup.
> >    * @imod_interval: set the interrupt moderation interval in 250ns
> >    *			increments or 0 to disable.
> >    * @max_cfg_eps: current max number of IN eps used across all USB configs.
> > @@ -1327,6 +1328,7 @@ struct dwc3 {
> >   
> >   	unsigned		dis_split_quirk:1;
> >   	unsigned		async_callbacks:1;
> > +	unsigned		wakeup_configured:1;
> >   
> >   	u16			imod_interval;
> >   
> > diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
> > index 61de693..f90fa55 100644
> > --- a/drivers/usb/dwc3/ep0.c
> > +++ b/drivers/usb/dwc3/ep0.c
> > @@ -356,6 +356,9 @@ static int dwc3_ep0_handle_status(struct dwc3 *dwc,
> >   				usb_status |= 1 << USB_DEV_STAT_U1_ENABLED;
> >   			if (reg & DWC3_DCTL_INITU2ENA)
> >   				usb_status |= 1 << USB_DEV_STAT_U2_ENABLED;
> > +		} else {
> > +			usb_status |= dwc->gadget->wakeup_armed <<
> > +					USB_DEVICE_REMOTE_WAKEUP;
> >   		}
> >   
> >   		break;
> > @@ -476,6 +479,7 @@ static int dwc3_ep0_handle_device(struct dwc3 *dwc,
> >   
> >   	switch (wValue) {
> >   	case USB_DEVICE_REMOTE_WAKEUP:
> > +		dwc->gadget->wakeup_armed = set;
> >   		break;
> >   	/*
> >   	 * 9.4.1 says only for SS, in AddressState only for
> > diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> > index 3c63fa9..b7fef5d 100644
> > --- a/drivers/usb/dwc3/gadget.c
> > +++ b/drivers/usb/dwc3/gadget.c
> > @@ -258,7 +258,7 @@ int dwc3_send_gadget_generic_command(struct dwc3 *dwc, unsigned int cmd,
> >   	return ret;
> >   }
> >   
> > -static int __dwc3_gadget_wakeup(struct dwc3 *dwc);
> > +static int __dwc3_gadget_wakeup(struct dwc3 *dwc, bool async);
> >   
> >   /**
> >    * dwc3_send_gadget_ep_cmd - issue an endpoint command
> > @@ -325,7 +325,7 @@ int dwc3_send_gadget_ep_cmd(struct dwc3_ep *dep, unsigned int cmd,
> >   
> >   			fallthrough;
> >   		case DWC3_LINK_STATE_U3:
> > -			ret = __dwc3_gadget_wakeup(dwc);
> > +			ret = __dwc3_gadget_wakeup(dwc, false);
> >   			dev_WARN_ONCE(dwc->dev, ret, "wakeup failed --> %d\n",
> >   					ret);
> >   			break;
> > @@ -2269,6 +2269,22 @@ static const struct usb_ep_ops dwc3_gadget_ep_ops = {
> >   
> >   /* -------------------------------------------------------------------------- */
> >   
> > +static void dwc3_gadget_enable_linksts_evts(struct dwc3 *dwc, bool set)
> > +{
> > +	u32 reg;
> > +
> > +	if (DWC3_VER_IS_PRIOR(DWC3, 250A))
> > +		return;
> > +
> > +	reg = dwc3_readl(dwc->regs, DWC3_DEVTEN);
> > +	if (set)
> > +		reg |= DWC3_DEVTEN_ULSTCNGEN;
> > +	else
> > +		reg &= ~DWC3_DEVTEN_ULSTCNGEN;
> > +
> > +	dwc3_writel(dwc->regs, DWC3_DEVTEN, reg);
> > +}
> > +
> >   static int dwc3_gadget_get_frame(struct usb_gadget *g)
> >   {
> >   	struct dwc3		*dwc = gadget_to_dwc(g);
> > @@ -2276,7 +2292,7 @@ static int dwc3_gadget_get_frame(struct usb_gadget *g)
> >   	return __dwc3_gadget_get_frame(dwc);
> >   }
> >   
> > -static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
> > +static int __dwc3_gadget_wakeup(struct dwc3 *dwc, bool async)
> >   {
> >   	int			retries;
> >   
> > @@ -2307,9 +2323,13 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
> >   		return -EINVAL;
> >   	}
> >   
> > +	if (async)
> > +		dwc3_gadget_enable_linksts_evts(dwc, true);
> > +
> >   	ret = dwc3_gadget_set_link_state(dwc, DWC3_LINK_STATE_RECOV);
> >   	if (ret < 0) {
> >   		dev_err(dwc->dev, "failed to put link in Recovery\n");
> > +		dwc3_gadget_enable_linksts_evts(dwc, false);
> >   		return ret;
> >   	}
> >   
> > @@ -2321,6 +2341,13 @@ static int __dwc3_gadget_wakeup(struct dwc3 *dwc)
> >   		dwc3_writel(dwc->regs, DWC3_DCTL, reg);
> >   	}
> >   
> > +	/*
> > +	 * Since link status change events are enabled we will receive
> > +	 * an U0 event when wakeup is successful. So bail out.
> > +	 */
> > +	if (async)
> > +		return 0;
> > +
> >   	/* poll until Link State changes to ON */
> >   	retries = 20000;
> >   
> > @@ -2346,13 +2373,36 @@ static int dwc3_gadget_wakeup(struct usb_gadget *g)
> >   	unsigned long		flags;
> >   	int			ret;
> >   
> > +	if (!dwc->wakeup_configured) {
> > +		dev_err(dwc->dev, "remote wakeup not configured\n");
> > +		return -EINVAL;
> > +	}
> > +
> >   	spin_lock_irqsave(&dwc->lock, flags);
> > -	ret = __dwc3_gadget_wakeup(dwc);
> > +	if (!dwc->gadget->wakeup_armed) {
> > +		dev_err(dwc->dev, "not armed for remote wakeup\n");
> > +		spin_unlock_irqrestore(&dwc->lock, flags);
> > +		return -EINVAL;
> > +	}
> > +	ret = __dwc3_gadget_wakeup(dwc, true);
> > +
> >   	spin_unlock_irqrestore(&dwc->lock, flags);
> >   
> >   	return ret;
> >   }
> >   
> > +static int dwc3_gadget_set_remote_wakeup(struct usb_gadget *g, int set)
> > +{
> > +	struct dwc3		*dwc = gadget_to_dwc(g);
> > +	unsigned long		flags;
> > +
> > +	spin_lock_irqsave(&dwc->lock, flags);
> > +	dwc->wakeup_configured = !!set;
> > +	spin_unlock_irqrestore(&dwc->lock, flags);
> > +
> > +	return 0;
> > +}
> > +
> >   static int dwc3_gadget_set_selfpowered(struct usb_gadget *g,
> >   		int is_selfpowered)
> >   {
> > @@ -2978,6 +3028,7 @@ static void dwc3_gadget_async_callbacks(struct usb_gadget *g, bool enable)
> >   static const struct usb_gadget_ops dwc3_gadget_ops = {
> >   	.get_frame		= dwc3_gadget_get_frame,
> >   	.wakeup			= dwc3_gadget_wakeup,
> > +	.set_remote_wakeup	= dwc3_gadget_set_remote_wakeup,
> >   	.set_selfpowered	= dwc3_gadget_set_selfpowered,
> >   	.pullup			= dwc3_gadget_pullup,
> >   	.udc_start		= dwc3_gadget_start,
> > @@ -3819,6 +3870,8 @@ static void dwc3_gadget_disconnect_interrupt(struct dwc3 *dwc)
> >   
> >   	dwc->gadget->speed = USB_SPEED_UNKNOWN;
> >   	dwc->setup_packet_pending = false;
> > +	dwc->gadget->wakeup_armed = false;
> > +	dwc3_gadget_enable_linksts_evts(dwc, false);
> >   	usb_gadget_set_state(dwc->gadget, USB_STATE_NOTATTACHED);
> >   
> >   	if (dwc->ep0state != EP0_SETUP_PHASE) {
> > @@ -3912,6 +3965,8 @@ static void dwc3_gadget_reset_interrupt(struct dwc3 *dwc)
> >   	reg &= ~DWC3_DCTL_TSTCTRL_MASK;
> >   	dwc3_gadget_dctl_write_safe(dwc, reg);
> >   	dwc->test_mode = false;
> > +	dwc->gadget->wakeup_armed = false;
> > +	dwc3_gadget_enable_linksts_evts(dwc, false);
> >   	dwc3_clear_stall_all_ep(dwc);
> >   
> >   	/* Reset device address to zero */
> > @@ -4064,7 +4119,7 @@ static void dwc3_gadget_conndone_interrupt(struct dwc3 *dwc)
> >   	 */
> >   }
> >   
> > -static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc)
> > +static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc, unsigned int evtinfo)
> >   {
> >   	/*
> >   	 * TODO take core out of low power mode when that's
> > @@ -4076,6 +4131,8 @@ static void dwc3_gadget_wakeup_interrupt(struct dwc3 *dwc)
> >   		dwc->gadget_driver->resume(dwc->gadget);
> >   		spin_lock(&dwc->lock);
> >   	}
> > +
> > +	dwc->link_state = evtinfo & DWC3_LINK_STATE_MASK;
> >   }
> >   
> >   static void dwc3_gadget_linksts_change_interrupt(struct dwc3 *dwc,
> > @@ -4157,6 +4214,10 @@ static void dwc3_gadget_linksts_change_interrupt(struct dwc3 *dwc,
> >   	}
> >   
> >   	switch (next) {
> > +	case DWC3_LINK_STATE_U0:
> > +		dwc3_gadget_enable_linksts_evts(dwc, false);
> > +		dwc3_resume_gadget(dwc);
>
> I don't think this should be a problem for dwc_usb3 2.50a and prior. But
> for a device that enables link state change event all the time, it would
> call this every time link transitions to U0. I'm not sure what the side
> effect can be. Can we add a wakeup_armed check here to prevent possible
> regression?
>
> Thanks,
> Thinh
Sure. I will upload v5 with this modification.

Thanks
Elson
> > +		break;
> >   	case DWC3_LINK_STATE_U1:
> >   		if (dwc->speed == USB_SPEED_SUPER)
> >   			dwc3_suspend_gadget(dwc);
> > @@ -4225,7 +4286,7 @@ static void dwc3_gadget_interrupt(struct dwc3 *dwc,
> >   		dwc3_gadget_conndone_interrupt(dwc);
> >   		break;
> >   	case DWC3_DEVICE_EVENT_WAKEUP:
> > -		dwc3_gadget_wakeup_interrupt(dwc);
> > +		dwc3_gadget_wakeup_interrupt(dwc, event->event_info);
> >   		break;
> >   	case DWC3_DEVICE_EVENT_HIBER_REQ:
> >   		if (dev_WARN_ONCE(dwc->dev, !dwc->has_hibernation,
> > @@ -4485,6 +4546,7 @@ int dwc3_gadget_init(struct dwc3 *dwc)
> >   	dwc->gadget->sg_supported	= true;
> >   	dwc->gadget->name		= "dwc3-gadget";
> >   	dwc->gadget->lpm_capable	= !dwc->usb2_gadget_lpm_disable;
> > +	dwc->gadget->wakeup_capable	= true;
> >   
> >   	/*
> >   	 * FIXME We might be setting max_speed to <SUPER, however versions
> > --
> > 2.7.4