USB: s3c-hsotg: Only load packet per fifo write

Limit the IN FIFO write to a single packet per attempt at writing,
as per the specifications and ensure that we don't return fifo-full
so that we can continue writing packets if we have the space.

Signed-off-by: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 11 insertions, 0 deletions

diff --git a/drivers/usb/gadget/s3c-hsotg.c b/drivers/usb/gadget/s3c-hsotg.c
index 4196e376a346..df6a39d6270f 100644
--- a/drivers/usb/gadget/s3c-hsotg.c
+++ b/drivers/usb/gadget/s3c-hsotg.c
@@ -538,6 +538,17 @@ static int s3c_hsotg_write_fifo(struct s3c_hsotg *hsotg,
         if (can_write > 512)
                 can_write = 512;
 
+        /* limit the write to one max-packet size worth of data, but allow
+         * the transfer to return that it did not run out of fifo space
+         * doing it. */
+        if (to_write > hs_ep->ep.maxpacket) {
+                to_write = hs_ep->ep.maxpacket;
+
+                s3c_hsotg_en_gsint(hsotg,
+                                   periodic ? S3C_GINTSTS_PTxFEmp :
+                                   S3C_GINTSTS_NPTxFEmp);
+        }
+
         /* see if we can write data */
 
         if (to_write > can_write) {