usb: dwc3: gadget: stop touching HWO TRBs

Say we have three requests prepared to the HW (reqA,
reqB, and reqC). All of them are composed of
SG-lists with several entries and they all requests
interrupt only on last TRBs of the SG-list.

When we get interrupt for reqA, it could be that
reqB is already half-way transferred and some of its
TRBs will have HWO already cleared.

It's okay to free up TRBs without HWO bit set, but
we need to guarantee we don't giveback a request
that's half-way transferred as that will confuse
gadget drivers.
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/gadget.c

@@ -2104,6 +2104,9 @@ static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
 			for_each_sg(sg, s, pending, i) {
 				trb = &dep->trb_pool[dep->trb_dequeue];
 
+				if (trb->ctrl & DWC3_TRB_CTRL_HWO)
+					break;
+
 				req->sg = sg_next(s);
 				req->num_pending_sgs--;