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Commit fd141fa4 authored by Sinan Kaya's avatar Sinan Kaya Committed by David S. Miller
Browse files

bnxt_en: Eliminate duplicate barriers on weakly-ordered archs 



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: default avatarSinan Kaya <okaya@codeaurora.org>
Acked-by: default avatarMichael Chan <michael.chan@broadcom.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent e42d8cee

drivers/net/ethernet/broadcom/bnxt/bnxt.c

+1 −1
Original line number Diff line number Diff line
@@ -1922,7 +1922,7 @@ static int bnxt_poll_work(struct bnxt *bp, struct bnxt_napi *bnapi, int budget) 
		/* 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;

drivers/net/ethernet/broadcom/bnxt/bnxt.h

+9 −0
Original line number Diff line number Diff line
@@ -1402,6 +1402,15 @@ static inline u32 bnxt_tx_avail(struct bnxt *bp, struct bnxt_tx_ring_info *txr) 
		((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)

{