From: Sinan Kaya <okaya@codeaurora.org>
Date: Tue, 13 Mar 2018 23:20:24 -0400
Subject: RDMA/qedr: eliminate duplicate barriers on weakly-ordered archs
Patch-mainline: v4.17-rc1
Git-commit: 561e5d48968be22fc71af6a0e13af6edae595dbe
References: bsc#1086314 FATE#324886 bsc#1086313 FATE#324885 bsc#1086301 FATE#3248881

Code includes wmb() followed by writel() in multiple places. writel()
already has a barrier on some architectures like arm64.

This ends up CPU observing two barriers back to back before executing the
register write.

Since code already has an explicit barrier call, changing writel() to
writel_relaxed().

Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/infiniband/hw/qedr/verbs.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/drivers/infiniband/hw/qedr/verbs.c
+++ b/drivers/infiniband/hw/qedr/verbs.c
@@ -1871,7 +1871,7 @@ static int qedr_update_qp_state(struct q
 
 			if (rdma_protocol_roce(&dev->ibdev, 1)) {
 				wmb();
-				writel(qp->rq.db_data.raw, qp->rq.db);
+				writel_relaxed(qp->rq.db_data.raw, qp->rq.db);
 				/* Make sure write takes effect */
 				mmiowb();
 			}
@@ -3276,7 +3276,7 @@ int qedr_post_send(struct ib_qp *ibqp, s
 	 * redundant doorbell.
 	 */
 	wmb();
-	writel(qp->sq.db_data.raw, qp->sq.db);
+	writel_relaxed(qp->sq.db_data.raw, qp->sq.db);
 
 	/* Make sure write sticks */
 	mmiowb();