usb: musb: gadget: restart request on clearing endpoint halt

Commit 46034dca515bc4ddca0399ae58106d1f5f0d809f (USB: musb_gadget_ep0: stop
abusing musb_gadget_set_halt()) forgot to restart a queued request after
clearing the endpoint halt feature. This results in a couple of USB resets
while enumerating the file-backed storage gadget due to CSW packet not being
sent for the MODE SENSE(10) command.

Signed-off-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Cc: stable@kernel.org
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/musb/musb_gadget.c

@@ -1084,7 +1084,7 @@ struct free_record {
 /*
  * Context: controller locked, IRQs blocked.
  */
-static void musb_ep_restart(struct musb *musb, struct musb_request *req)
+void musb_ep_restart(struct musb *musb, struct musb_request *req)
 {
 	DBG(3, "<== %s request %p len %u on hw_ep%d\n",
 		req->tx ? "TX/IN" : "RX/OUT",

drivers/usb/musb/musb_gadget.h

@@ -105,4 +105,6 @@ extern void musb_gadget_cleanup(struct musb *);
 
 extern void musb_g_giveback(struct musb_ep *, struct usb_request *, int);
 
+extern void musb_ep_restart(struct musb *, struct musb_request *);
+
 #endif		/* __MUSB_GADGET_H */

drivers/usb/musb/musb_gadget_ep0.c

@@ -261,6 +261,7 @@ __acquires(musb->lock)
 					ctrlrequest->wIndex & 0x0f;
 				struct musb_ep		*musb_ep;
 				struct musb_hw_ep	*ep;
+				struct musb_request	*request;
 				void __iomem		*regs;
 				int			is_in;
 				u16			csr;
@@ -302,6 +303,14 @@ __acquires(musb->lock)
 					musb_writew(regs, MUSB_RXCSR, csr);
 				}
 
+				/* Maybe start the first request in the queue */
+				request = to_musb_request(
+						next_request(musb_ep));
+				if (!musb_ep->busy && request) {
+					DBG(3, "restarting the request\n");
+					musb_ep_restart(musb, request);
+				}
+
 				/* select ep0 again */
 				musb_ep_select(mbase, 0);
 				} break;