[PATCH] USB: DWC3: Fix missed isoc IN transaction

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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.
Only limitation is that, gadget will have to submit a request within 4
uf time, which dwc3 driver considers safe enough for staring a new
transfer.

Signed-off-by: Pratyush Anand <pratyush.anand@xxxxxx>
---
 drivers/usb/dwc3/core.h   |    3 +++
 drivers/usb/dwc3/gadget.c |   36 +++++++++++++++++++++++++++++++-----
 2 files changed, 34 insertions(+), 5 deletions(-)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 2a920f8..c3f61f6 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -352,6 +352,7 @@ struct dwc3_event_buffer {
  * @number: endpoint number (1 - 15)
  * @type: set to bmAttributes & USB_ENDPOINT_XFERTYPE_MASK
  * @res_trans_idx: Resource transfer index
+ * @event: pointer to event struct received during missed isoc xferinprogress
  * @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
@@ -376,6 +377,7 @@ 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)
@@ -385,6 +387,7 @@ struct dwc3_ep {
 	u8			number;
 	u8			type;
 	u8			res_trans_idx;
+	const struct dwc3_event_depevt *event;
 	u32			interval;
 
 	char			name[20];
diff --git a/drivers/usb/dwc3/gadget.c b/drivers/usb/dwc3/gadget.c
index 9affe67..5a9f1f19 100644
--- a/drivers/usb/dwc3/gadget.c
+++ b/drivers/usb/dwc3/gadget.c
@@ -995,6 +995,9 @@ 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, const struct dwc3_event_depevt *event);
+
 static int __dwc3_gadget_ep_queue(struct dwc3_ep *dep, struct dwc3_request *req)
 {
 	struct dwc3		*dwc = dep->dwc;
@@ -1024,8 +1027,19 @@ 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->desc) && (dep->flags & DWC3_EP_BUSY))
-		dep->flags |= DWC3_EP_PENDING_REQUEST;
+	if (usb_endpoint_xfer_isoc(dep->desc)) {
+		if (dep->flags & DWC3_EP_BUSY) {
+			dep->flags |= DWC3_EP_PENDING_REQUEST;
+		} else if (dep->flags & DWC3_EP_MISSED_ISOC) {
+			/*
+			 * FIXME: Only case which I still see failing is
+			 * if gadget delays submission for more than 4
+			 * uf time.
+			 */
+			dwc3_gadget_start_isoc(dwc, dep, dep->event);
+			dep->flags &= ~DWC3_EP_MISSED_ISOC;
+		}
+	}
 
 	/*
 	 * There are two special cases:
@@ -1590,6 +1604,7 @@ 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		m_isoc = 0;
 
 	do {
 		req = next_request(&dep->req_queued);
@@ -1615,9 +1630,18 @@ static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
 
 		if (dep->direction) {
 			if (count) {
-				dev_err(dwc->dev, "incomplete IN transfer %s\n",
-						dep->name);
-				status = -ECONNRESET;
+				if (usb_endpoint_xfer_isoc(dep->desc)) {
+					dev_dbg(dwc->dev, "incomplete IN \
+							transfer %s\n",
+							dep->name);
+					dep->flags |= DWC3_EP_MISSED_ISOC;
+					dep->event = event;
+				} else {
+					dev_err(dwc->dev, "incomplete IN \
+							transfer %s\n",
+							dep->name);
+					status = -ECONNRESET;
+				}
 			}
 		} else {
 			if (count && (event->status & DEPEVT_STATUS_SHORT))
@@ -1635,6 +1659,8 @@ static int dwc3_cleanup_done_reqs(struct dwc3 *dwc, struct dwc3_ep *dep,
 		dwc3_gadget_giveback(dep, req, status);
 		if (s_pkt)
 			break;
+		if (m_isoc)
+			break;
 		if ((event->status & DEPEVT_STATUS_LST) &&
 				(trb->ctrl & DWC3_TRB_CTRL_LST))
 			break;
-- 
1.7.5.4

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