usb: gadget: hid: don't STALL when processing a HID Descriptor request

This is a patch to fix an issue with the HID gadget which, at the moment,
returns STALL on a HID descriptor request. Essentially, the patch changes
the hid gadget such that a request for the HID descriptor is handled by
copying the descriptor into the response buffer, rather than falling
through the default case, in which the request is answered by a STALL.
Signed-off-by: Sebastian Bauer <mail@sebastianbauer.info>
Acked-by: Peter Korsgaard <peter.korsgaard@barco.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/gadget/f_hid.c

@@ -367,6 +367,13 @@ static int hidg_setup(struct usb_function *f,
 	case ((USB_DIR_IN | USB_TYPE_STANDARD | USB_RECIP_INTERFACE) << 8
 		  | USB_REQ_GET_DESCRIPTOR):
 		switch (value >> 8) {
+		case HID_DT_HID:
+			VDBG(cdev, "USB_REQ_GET_DESCRIPTOR: HID\n");
+			length = min_t(unsigned short, length,
+						   hidg_desc.bLength);
+			memcpy(req->buf, &hidg_desc, length);
+			goto respond;
+			break;
 		case HID_DT_REPORT:
 			VDBG(cdev, "USB_REQ_GET_DESCRIPTOR: REPORT\n");
 			length = min_t(unsigned short, length,