[PATCH v4 6/7] scsi: bnx2i: Eliminate duplicate barriers on weakly-ordered archs

Sinan Kaya okaya at codeaurora.org
Mon Mar 19 19:50:06 PDT 2018


Code includes barrier() 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.

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

Signed-off-by: Sinan Kaya <okaya at codeaurora.org>
---
 drivers/scsi/bnx2i/bnx2i_hwi.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/scsi/bnx2i/bnx2i_hwi.c b/drivers/scsi/bnx2i/bnx2i_hwi.c
index 8f03a86..075735b 100644
--- a/drivers/scsi/bnx2i/bnx2i_hwi.c
+++ b/drivers/scsi/bnx2i/bnx2i_hwi.c
@@ -278,7 +278,7 @@ static void bnx2i_ring_sq_dbell(struct bnx2i_conn *bnx2i_conn, int count)
 		sq_db->prod_idx = ep->qp.sq_prod_idx;
 		bnx2i_ring_577xx_doorbell(bnx2i_conn);
 	} else
-		writew(count, ep->qp.ctx_base + CNIC_SEND_DOORBELL);
+		writew_relaxed(count, ep->qp.ctx_base + CNIC_SEND_DOORBELL);
 
 	mmiowb(); /* flush posted PCI writes */
 }
-- 
2.7.4




More information about the linux-arm-kernel mailing list