fsl_usb2_udc: Add a wmb before priming endpoint.

Add a wmb to fsl_queue_td before priming the endpoint. This ensures that the
modifications to the QH are seen by the hardware.

Added comment as suggested by Felipe Balbi.

Signed-off-by: Will Newton <will.newton@gmail.com>
Acked-by: Li Yang <leoli@freescale.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/usb/gadget/fsl_usb2_udc.c b/drivers/usb/gadget/fsl_usb2_udc.c
index 6f6272031344..0492441bc0ba 100644
--- a/drivers/usb/gadget/fsl_usb2_udc.c
+++ b/drivers/usb/gadget/fsl_usb2_udc.c
@@ -643,6 +643,9 @@ static void fsl_queue_td(struct fsl_ep *ep, struct fsl_req *req)
                         | EP_QUEUE_HEAD_STATUS_HALT));
         dQH->size_ioc_int_sts &= temp;
 
+        /* Ensure that updates to the QH will occure before priming. */
+        wmb();
+
         /* Prime endpoint by writing 1 to ENDPTPRIME */
         temp = ep_is_in(ep)
                 ? (1 << (ep_index(ep) + 16))