From: Sinan Kaya <okaya@codeaurora.org>
Date: Sun, 25 Mar 2018 10:39:20 -0400
Subject: bnxt_en: Eliminate duplicate barriers on weakly-ordered archs
Patch-mainline: v4.17-rc1
Git-commit: fd141fa47c03018aa1f77c335b0f444493e145d5
References: bsc#1086282 FATE#324873
Code includes wmb() followed by writel(). 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.
Create a new wrapper function with relaxed write operator. Use the new
wrapper when a write is following a wmb().
Since code already has an explicit barrier call, changing writel() to
writel_relaxed().
Also add mmiowb() so that write code doesn't move outside of scope.
Signed-off-by: Sinan Kaya <okaya@codeaurora.org>
Acked-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
drivers/net/ethernet/broadcom/bnxt/bnxt.c | 2 +-
drivers/net/ethernet/broadcom/bnxt/bnxt.h | 9 +++++++++
2 files changed, 10 insertions(+), 1 deletion(-)
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.c
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.c
@@ -1918,7 +1918,7 @@ static int bnxt_poll_work(struct bnxt *b
/* Sync BD data before updating doorbell */
wmb();
- bnxt_db_write(bp, db, DB_KEY_TX | prod);
+ bnxt_db_write_relaxed(bp, db, DB_KEY_TX | prod);
}
cpr->cp_raw_cons = raw_cons;
--- a/drivers/net/ethernet/broadcom/bnxt/bnxt.h
+++ b/drivers/net/ethernet/broadcom/bnxt/bnxt.h
@@ -1392,6 +1392,15 @@ static inline u32 bnxt_tx_avail(struct b
((txr->tx_prod - txr->tx_cons) & bp->tx_ring_mask);
}
+/* For TX and RX ring doorbells with no ordering guarantee*/
+static inline void bnxt_db_write_relaxed(struct bnxt *bp, void __iomem *db,
+ u32 val)
+{
+ writel_relaxed(val, db);
+ if (bp->flags & BNXT_FLAG_DOUBLE_DB)
+ writel_relaxed(val, db);
+}
+
/* For TX and RX ring doorbells */
static inline void bnxt_db_write(struct bnxt *bp, void __iomem *db, u32 val)
{