1 files changed, 32 insertions, 2 deletions

diff --git a/drivers/usb/gadget/s3c-hsotg.c b/drivers/usb/gadget/s3c-hsotg.c
index 7b46af3e014..0a74a067749 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__);