Re: [RFC][PATCH] usb: dwc3: usb: dwc3: Force stop EP0 transfers during pullup disable

[Thinh Nguyen]

Wesley Cheng wrote:
> During a USB cable disconnect, or soft disconnect scenario, a pending
> SETUP transaction may not be completed, leading to the following
> error:
> 
>     dwc3 a600000.dwc3: timed out waiting for SETUP phase

How could it be a case of cable disconnect? The pullup(0) only applies
for soft-disconnect scenario. If the device initiated a disconnect, then
the driver should wait for the control request to complete. If it times
out, something is already wrong here. The programming guide only
mentions that we should wait for completion, but it doesn't say about
recovery in a case of hung transfer. I need to check internally but it
should be safe to issue End Transfer.

> 
> If this occurs, then the entire pullup disable routine is skipped and
> proper cleanup and halting of the controller does not complete.
> Instead of returning an error (which is ignored from the UDC
> perspective), do what is mentioned in the comments and force the
> transaction to complete and put the ep0state back to the SETUP phase.
> 
> Signed-off-by: Wesley Cheng <wcheng@xxxxxxxxxxxxxx>
> ---
>  drivers/usb/dwc3/ep0.c    | 4 ++--
>  drivers/usb/dwc3/gadget.c | 6 +++++-
>  drivers/usb/dwc3/gadget.h | 3 +++
>  3 files changed, 10 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/usb/dwc3/ep0.c b/drivers/usb/dwc3/ep0.c
> index 6587394..abfc42b 100644
> --- a/drivers/usb/dwc3/ep0.c
> +++ b/drivers/usb/dwc3/ep0.c
> @@ -218,7 +218,7 @@ int dwc3_gadget_ep0_queue(struct usb_ep *ep, struct usb_request *request,
>  	return ret;
>  }
>  
> -static void dwc3_ep0_stall_and_restart(struct dwc3 *dwc)
> +void dwc3_ep0_stall_and_restart(struct dwc3 *dwc)
>  {
>  	struct dwc3_ep		*dep;
>  
> @@ -1073,7 +1073,7 @@ void dwc3_ep0_send_delayed_status(struct dwc3 *dwc)
>  	__dwc3_ep0_do_control_status(dwc, dwc->eps[direction]);
>  }
>  
> -static void dwc3_ep0_end_control_data(struct dwc3 *dwc, struct dwc3_ep *dep)
> +void dwc3_ep0_end_control_data(struct dwc3 *dwc, struct dwc3_ep *dep)
>  {
>  	struct dwc3_gadget_ep_cmd_params params;
>  	u32			cmd;
> diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
> index 54c5a08..a0e2e4d 100644
> --- a/drivers/usb/dwc3/gadget.c
> +++ b/drivers/usb/dwc3/gadget.c
> @@ -2437,7 +2437,11 @@ static int dwc3_gadget_pullup(struct usb_gadget *g, int is_on)
>  				msecs_to_jiffies(DWC3_PULL_UP_TIMEOUT));
>  		if (ret == 0) {
>  			dev_err(dwc->dev, "timed out waiting for SETUP phase\n");
> -			return -ETIMEDOUT;
> +			spin_lock_irqsave(&dwc->lock, flags);
> +			dwc3_ep0_end_control_data(dwc, dwc->eps[0]);
> +			dwc3_ep0_end_control_data(dwc, dwc->eps[1]);

End transfer command takes time, need to wait for it to complete before
issuing Start transfer again. Also, why restart again when it's about to
be disconnected.

We'd also need to watch out for soft-connect in quick succession before
the End Transfer command completes.

> +			dwc3_ep0_stall_and_restart(dwc);
> +			spin_unlock_irqrestore(&dwc->lock, flags);
>  		}
>  	}
>  
> diff --git a/drivers/usb/dwc3/gadget.h b/drivers/usb/dwc3/gadget.h
> index 77df4b6..632f7b7 100644
> --- a/drivers/usb/dwc3/gadget.h
> +++ b/drivers/usb/dwc3/gadget.h
> @@ -114,6 +114,9 @@ int __dwc3_gadget_ep0_set_halt(struct usb_ep *ep, int value);
>  int dwc3_gadget_ep0_set_halt(struct usb_ep *ep, int value);
>  int dwc3_gadget_ep0_queue(struct usb_ep *ep, struct usb_request *request,
>  		gfp_t gfp_flags);
> +void dwc3_ep0_stall_and_restart(struct dwc3 *dwc);
> +void dwc3_ep0_end_control_data(struct dwc3 *dwc, struct dwc3_ep *dep);
> +
>  int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value, int protocol);
>  void dwc3_ep0_send_delayed_status(struct dwc3 *dwc);
>  
> 

BR,
Thinh