GenWQE: Add wmb before DDCB is started

Needed to add wmb() before we send the DDCB for execution.
Without the syncronizing it failed on System p.

Signed-off-by: Frank Haverkamp <haver@linux.vnet.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 4 insertions, 0 deletions

diff --git a/drivers/misc/genwqe/card_ddcb.c b/drivers/misc/genwqe/card_ddcb.c
index 6f1acc0ccf88..29a1a28be02a 100644
--- a/drivers/misc/genwqe/card_ddcb.c
+++ b/drivers/misc/genwqe/card_ddcb.c
@@ -305,6 +305,8 @@ static int enqueue_ddcb(struct genwqe_dev *cd, struct ddcb_queue *queue,
                         break;
 
                 new = (old | DDCB_NEXT_BE32);
+
+                wmb();
                 icrc_hsi_shi = cmpxchg(&prev_ddcb->icrc_hsi_shi_32, old, new);
 
                 if (icrc_hsi_shi == old)
@@ -314,6 +316,8 @@ static int enqueue_ddcb(struct genwqe_dev *cd, struct ddcb_queue *queue,
         /* Queue must be re-started by updating QUEUE_OFFSET */
         ddcb_mark_tapped(pddcb);
         num = (u64)ddcb_no << 8;
+
+        wmb();
         __genwqe_writeq(cd, queue->IO_QUEUE_OFFSET, num); /* start queue */
 
         return RET_DDCB_TAPPED;