usb: dwc3: gadget: cache frame number in struct dwc3_ep

This is in preparation to simplifying prototype of
__dwc3_gadget_kick_transfer().
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/dwc3/core.h

@@ -529,6 +529,7 @@ struct dwc3_event_buffer {
  * @number: endpoint number (1 - 15)
  * @type: set to bmAttributes & USB_ENDPOINT_XFERTYPE_MASK
  * @resource_index: Resource transfer index
+ * @frame_number: set to the frame number we want this transfer to start (ISOC)
  * @interval: the interval on which the ISOC transfer is started
  * @allocated_requests: number of requests allocated
  * @queued_requests: number of requests queued for transfer
@@ -581,6 +582,7 @@ struct dwc3_ep {
 	u8			resource_index;
 	u32			allocated_requests;
 	u32			queued_requests;
+	u32			frame_number;
 	u32			interval;
 
 	char			name[20];

drivers/usb/dwc3/gadget.c

@@ -1258,8 +1258,6 @@ static int __dwc3_gadget_get_frame(struct dwc3 *dwc)
 static void __dwc3_gadget_start_isoc(struct dwc3 *dwc,
 		struct dwc3_ep *dep, u32 cur_uf)
 {
-	u32 uf;
-
 	if (list_empty(&dep->pending_list)) {
 		dev_info(dwc->dev, "%s: ran out of requests\n",
 				dep->name);
@@ -1271,9 +1269,8 @@ static void __dwc3_gadget_start_isoc(struct dwc3 *dwc,
 	 * Schedule the first trb for one interval in the future or at
 	 * least 4 microframes.
 	 */
-	uf = cur_uf + max_t(u32, 4, dep->interval);
-
-	__dwc3_gadget_kick_transfer(dep, uf);
+	dep->frame_number = cur_uf + max_t(u32, 4, dep->interval);
+	__dwc3_gadget_kick_transfer(dep, dep->frame_number);
 }
 
 static void dwc3_gadget_start_isoc(struct dwc3 *dwc,