usb: dwc3: gadget: fix set_halt() bug with pending transfers

According to our Gadget Framework API documentation,
->set_halt() *must* return -EAGAIN if we have pending
transfers (on either direction) or FIFO isn't empty (on
TX endpoints).

Fix this bug so that the mass storage gadget can be used
without stall=0 parameter.

This patch should be backported to all kernels since v3.2.

Cc: <stable@vger.kernel.org> # v3.2+
Suggested-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Felipe Balbi <balbi@ti.com>

(cherry picked from commit 7a608559)
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

drivers/usb/dwc3/ep0.c

@@ -270,7 +270,7 @@ static void dwc3_ep0_stall_and_restart(struct dwc3 *dwc)
 
 	/* stall is always issued on EP0 */
 	dep = dwc->eps[0];
-	__dwc3_gadget_ep_set_halt(dep, 1);
+	__dwc3_gadget_ep_set_halt(dep, 1, false);
 	dep->flags = DWC3_EP_ENABLED;
 	dwc->delayed_status = false;
 
@@ -477,7 +477,7 @@ static int dwc3_ep0_handle_feature(struct dwc3 *dwc,
 				return -EINVAL;
 			if (set == 0 && (dep->flags & DWC3_EP_WEDGE))
 				break;
-			ret = __dwc3_gadget_ep_set_halt(dep, set);
+			ret = __dwc3_gadget_ep_set_halt(dep, set, true);
 			if (ret)
 				return -EINVAL;
 			break;

drivers/usb/dwc3/gadget.c

@@ -604,7 +604,7 @@ static int __dwc3_gadget_ep_disable(struct dwc3_ep *dep)
 
 	/* make sure HW endpoint isn't stalled */
 	if (dep->flags & DWC3_EP_STALL)
-		__dwc3_gadget_ep_set_halt(dep, 0);
+		__dwc3_gadget_ep_set_halt(dep, 0, false);
 
 	reg = dwc3_readl(dwc->regs, DWC3_DALEPENA);
 	reg &= ~DWC3_DALEPENA_EP(dep->number);
@@ -1196,7 +1196,7 @@ static int dwc3_gadget_ep_dequeue(struct usb_ep *ep,
 	return ret;
 }
 
-int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value)
+int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value, int protocol)
 {
 	struct dwc3_gadget_ep_cmd_params	params;
 	struct dwc3				*dwc = dep->dwc;
@@ -1205,6 +1205,14 @@ int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value)
 	memset(&params, 0x00, sizeof(params));
 
 	if (value) {
+		if (!protocol && ((dep->direction && dep->flags & DWC3_EP_BUSY) ||
+				(!list_empty(&dep->req_queued) ||
+				 !list_empty(&dep->request_list)))) {
+			dev_dbg(dwc->dev, "%s: pending request, cannot halt\n",
+					dep->name);
+			return -EAGAIN;
+		}
+
 		ret = dwc3_send_gadget_ep_cmd(dwc, dep->number,
 			DWC3_DEPCMD_SETSTALL, &params);
 		if (ret)
@@ -1244,7 +1252,7 @@ static int dwc3_gadget_ep_set_halt(struct usb_ep *ep, int value)
 		goto out;
 	}
 
-	ret = __dwc3_gadget_ep_set_halt(dep, value);
+	ret = __dwc3_gadget_ep_set_halt(dep, value, false);
 out:
 	spin_unlock_irqrestore(&dwc->lock, flags);
 
@@ -1264,7 +1272,7 @@ static int dwc3_gadget_ep_set_wedge(struct usb_ep *ep)
 	if (dep->number == 0 || dep->number == 1)
 		return dwc3_gadget_ep0_set_halt(ep, 1);
 	else
-		return dwc3_gadget_ep_set_halt(ep, 1);
+		return __dwc3_gadget_ep_set_halt(dep, 1, false);
 }
 
 /* -------------------------------------------------------------------------- */

drivers/usb/dwc3/gadget.h

@@ -114,7 +114,7 @@ void dwc3_ep0_out_start(struct dwc3 *dwc);
 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);
-int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value);
+int __dwc3_gadget_ep_set_halt(struct dwc3_ep *dep, int value, int protocol);
 int dwc3_send_gadget_ep_cmd(struct dwc3 *dwc, unsigned ep,
 		unsigned cmd, struct dwc3_gadget_ep_cmd_params *params);
 int dwc3_send_gadget_generic_command(struct dwc3 *dwc, int cmd, u32 param);