1 files changed, 32 insertions, 2 deletions

diff --git a/drivers/usb/gadget/s3c-hsotg.c b/drivers/usb/gadget/s3c-hsotg.c
index 7b46af3e014f..0a74a067749a 100644
--- a/drivers/usb/gadget/s3c-hsotg.c
+++ b/drivers/usb/gadget/s3c-hsotg.c
@@ -1555,6 +1555,10 @@ static void s3c_hsotg_handle_outdone(struct s3c_hsotg *hsotg,
 	}
 
 	if (epnum == 0) {
+		/*
+		 * Condition req->complete != s3c_hsotg_complete_setup says:
+		 * send ZLP when we have an asynchronous request from gadget
+		 */
 		if (!was_setup && req->complete != s3c_hsotg_complete_setup)
 			s3c_hsotg_send_zlp(hsotg, hs_req);
 	}
@@ -1809,6 +1813,13 @@ static void s3c_hsotg_complete_in(struct s3c_hsotg *hsotg,
 		return;
 	}
 
+	/* Finish ZLP handling for IN EP0 transactions */
+	if (hsotg->eps[0].sent_zlp) {
+		dev_dbg(hsotg->dev, "zlp packet received\n");
+		s3c_hsotg_complete_request_lock(hsotg, hs_ep, hs_req, 0);
+		return;
+	}
+
 	/* Calculate the size of the transfer by checking how much is left
 	 * in the endpoint size register and then working it out from
 	 * the amount we loaded for the transfer.
@@ -1828,9 +1839,28 @@ static void s3c_hsotg_complete_in(struct s3c_hsotg *hsotg,
 			__func__, hs_req->req.actual, size_done);
 
 	hs_req->req.actual = size_done;
+	dev_dbg(hsotg->dev, "req->length:%d req->actual:%d req->zero:%d\n",
+		hs_req->req.length, hs_req->req.actual, hs_req->req.zero);
+
+	/*
+	 * Check if dealing with Maximum Packet Size(MPS) IN transfer at EP0
+	 * When sent data is a multiple MPS size (e.g. 64B ,128B ,192B
+	 * ,256B ... ), after last MPS sized packet send IN ZLP packet to
+	 * inform the host that no more data is available.
+	 * The state of req.zero member is checked to be sure that the value to
+	 * send is smaller than wValue expected from host.
+	 * Check req.length to NOT send another ZLP when the current one is
+	 * under completion (the one for which this completion has been called).
+	 */
+	if (hs_req->req.length && hs_ep->index == 0 && hs_req->req.zero &&
+	    hs_req->req.length == hs_req->req.actual &&
+	    !(hs_req->req.length % hs_ep->ep.maxpacket)) {
+
+		dev_dbg(hsotg->dev, "ep0 zlp IN packet sent\n");
+		s3c_hsotg_send_zlp(hsotg, hs_req);
 
-	/* if we did all of the transfer, and there is more data left
-	 * around, then try restarting the rest of the request */
+		return;
+	}
 
 	if (!size_left && hs_req->req.actual < hs_req->req.length) {
 		dev_dbg(hsotg->dev, "%s trying more for req...\n", __func__);