usb: dwc3: Fix missed isoc IN transaction

If an IN transfer is missed on isoc endpoint, then driver must insure
that next ep_queue is properly handled.
This patch fixes this issue by starting a new transfer for next queued
request.
Signed-off-by: Pratyush Anand <pratyush.anand@st.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>

drivers/usb/dwc3/core.h

@@ -405,6 +405,7 @@ struct dwc3_event_buffer {
  * @number: endpoint number (1 - 15)
  * @type: set to bmAttributes & USB_ENDPOINT_XFERTYPE_MASK
  * @res_trans_idx: Resource transfer index
+ * @current_uf: Current uf received through last event parameter
  * @interval: the intervall on which the ISOC transfer is started
  * @name: a human readable name e.g. ep1out-bulk
  * @direction: true for TX, false for RX
@@ -428,6 +429,7 @@ struct dwc3_ep {
 #define DWC3_EP_WEDGE		(1 << 2)
 #define DWC3_EP_BUSY		(1 << 4)
 #define DWC3_EP_PENDING_REQUEST	(1 << 5)
+#define DWC3_EP_MISSED_ISOC	(1 << 6)
 
 	/* This last one is specific to EP0 */
 #define DWC3_EP0_DIR_IN		(1 << 31)
@@ -437,6 +439,7 @@ struct dwc3_ep {
 	u8			number;
 	u8			type;
 	u8			res_trans_idx;
+	u16			current_uf;
 	u32			interval;
 
 	char			name[20];

drivers/usb/dwc3/gadget.c

@@ -990,6 +990,34 @@ static int __dwc3_gadget_kick_transfer(struct dwc3_ep *dep, u16 cmd_param,
 	return 0;
 }
 
+static void __dwc3_gadget_start_isoc(struct dwc3 *dwc,
+		struct dwc3_ep *dep, u32 cur_uf)
+{
+	u32 uf;
+
+	if (list_empty(&dep->request_list)) {
+		dev_vdbg(dwc->dev, "ISOC ep %s run out for requests.\n",
+			dep->name);
+		return;
+	}
+
+	/* 4 micro frames in the future */
+	uf = cur_uf + dep->interval * 4;
+
+	__dwc3_gadget_kick_transfer(dep, uf, 1);
+}
+
+static void dwc3_gadget_start_isoc(struct dwc3 *dwc,
+		struct dwc3_ep *dep, const struct dwc3_event_depevt *event)
+{
+	u32 cur_uf, mask;
+
+	mask = ~(dep->interval - 1);
+	cur_uf = event->parameters & mask;
+
+	__dwc3_gadget_start_isoc(dwc, dep, cur_uf);
+}
+
 static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
 {
 	struct dwc3		*dwc = dep->dwc;
@@ -1019,8 +1047,14 @@ static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
 
 	list_add_tail(&req->list, &dep->request_list);
 
-	if (usb_endpoint_xfer_isoc(dep->endpoint.desc) && (dep->flags & DWC3_EP_BUSY))
+	if (usb_endpoint_xfer_isoc(dep->endpoint.desc)) {
+		if (dep->flags & DWC3_EP_BUSY) {
 			dep->flags |= DWC3_EP_PENDING_REQUEST;
+		} else if (dep->flags & DWC3_EP_MISSED_ISOC) {
+			__dwc3_gadget_start_isoc(dwc, dep, dep->current_uf);
+			dep->flags &= ~DWC3_EP_MISSED_ISOC;
+		}
+	}
 
 	/*
 	 * There are two special cases:
@@ -1591,6 +1625,7 @@ static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
 	struct dwc3_trb		*trb;
 	unsigned int		count;
 	unsigned int		s_pkt = 0;
+	unsigned int		trb_status;
 
 	do {
 		req = next_request(&dep->req_queued);
@@ -1616,10 +1651,19 @@ static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
 
 		if (dep->direction) {
 			if (count) {
+				trb_status = DWC3_TRB_SIZE_TRBSTS(trb->size);
+				if (trb_status == DWC3_TRBSTS_MISSED_ISOC) {
+					dev_dbg(dwc->dev, "incomplete IN transfer %s\n",
+							dep->name);
+					dep->current_uf = event->parameters &
+						~(dep->interval - 1);
+					dep->flags |= DWC3_EP_MISSED_ISOC;
+				} else {
 					dev_err(dwc->dev, "incomplete IN transfer %s\n",
 							dep->name);
 					status = -ECONNRESET;
 				}
+			}
 		} else {
 			if (count && (event->status & DEPEVT_STATUS_SHORT))
 				s_pkt = 1;
@@ -1690,25 +1734,6 @@ static void dwc3_endpoint_transfer_complete(struct dwc3 *dwc,
 	}
 }
 
-static void dwc3_gadget_start_isoc(struct dwc3 *dwc,
-		struct dwc3_ep *dep, const struct dwc3_event_depevt *event)
-{
-	u32 uf, mask;
-
-	if (list_empty(&dep->request_list)) {
-		dev_vdbg(dwc->dev, "ISOC ep %s run out for requests.\n",
-			dep->name);
-		return;
-	}
-
-	mask = ~(dep->interval - 1);
-	uf = event->parameters & mask;
-	/* 4 micro frames in the future */
-	uf += dep->interval * 4;
-
-	__dwc3_gadget_kick_transfer(dep, uf, 1);
-}
-
 static void dwc3_process_ep_cmd_complete(struct dwc3_ep *dep,
 		const struct dwc3_event_depevt *event)
 {