Re: [PATCH v3] usb: dwc3: gadget: Prevent EP resource conflicts during StartTransfer

[Thinh Nguyen <Thinh.Nguyen@synopsys.com>]

On Tue, Oct 06, 2026, Selvarasu Ganesan wrote:
> 
> >   	/* Clear out the ep descriptors for non-ep0 */
> > @@ -1792,9 +1815,9 @@ static int __dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool int
> >   
> >   	dep->resource_index = 0;
> >   
> > -	if (!interrupt)
> > +	if (!interrupt || ret)
> 
> 
> Hi Thinh,
> 
> Thanks for your code changes. The given code changes look good to me and 
> are working as expected.
> 
> There is one more concern about an uncovered endpoint resource failure 
> in some corner cases where END TRANSFER timeout is observed (ret = -110).
> 
> The sequence is explained below,
> 
> Step 1:
>   __dwc3_gadget_ep_set_halt(dep, value=0)
>    ->dwc3_stop_active_transfer(dep, true, true)

Looks like you still do ForceRM=true. Can you apply this patch:

  b58e6200450d ("usb: dwc3: clear forceRM when issuing EndTransfer")

>      ->END(e.g, ep2out, resource_index=7) issued, but timeout occurs
>       -> resource_index cleared to 0
>    ->dwc3_send_clear_stall_ep_cmd(dep)
>      -> failed to clear STALL on ep2out
> 
> 
> Step 2:
> __dwc3_gadget_ep_set_halt(dep, value=0) ->Re triggered clear stall for 
> same EP
>   -> dwc3_stop_active_transfer(dep, true, true)
>     -> END(ep2out, resource_index=0) issued (wrong resource!)
>       -> Command succeeds, DWC3_EP_TRANSFER_STARTED cleared in 
> completion handler
> 
> Step 3:
> usb_ep_queue()
>   -> dwc3_gadget_ep_queue()
>     -> __dwc3_gadget_kick_transfer()
>       -> starting = !(dep->flags & DWC3_EP_TRANSFER_STARTED)  -> starting=0
>         -> Issues STARTTRANSFER (because DWC3_EP_TRANSFER_STARTED is not 
> set)
>           -> Hardware rejects with NO_RESOURCE (resource 7 still held)
> 
> 
> Could you please give your suggestions on this issue case?
> 

Thanks for testing. Can you check whether the End Transfer command ever
completes with the endpoint completion event after the -ETIMEDOUT error?
Try with the below.

Thanks,
Thinh

diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 1f973e546219..bac0328423cd 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -1819,7 +1819,11 @@ static int __dwc3_stop_active_transfer(struct dwc3_ep *dep, bool force, bool int
 
 	dep->resource_index = 0;
 
-	if (!interrupt || ret)
+	if (!interrupt || (ret && ret != -ETIMEDOUT))
 		dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
 	else
 		dep->flags |= DWC3_EP_END_TRANSFER_PENDING;
@@ -3895,6 +3899,8 @@ static void dwc3_gadget_endpoint_command_complete(struct dwc3_ep *dep,
 	if (dep->stream_capable)
 		dep->flags |= DWC3_EP_IGNORE_NEXT_NOSTREAM;
 
+	dep->flags &= ~DWC3_EP_DELAY_STOP;
 	dep->flags &= ~DWC3_EP_END_TRANSFER_PENDING;
 	dep->flags &= ~DWC3_EP_TRANSFER_STARTED;
 	dwc3_gadget_ep_cleanup_cancelled_requests(dep);