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From: Sinan Kaya <okaya@codeaurora.org>
To: linux-scsi@vger.kernel.org, timur@codeaurora.org, sulrich@codeaurora.org
Cc: linux-arm-msm@vger.kernel.org,
	linux-arm-kernel@lists.infradead.org,
	Sinan Kaya <okaya@codeaurora.org>,
	QLogic-Storage-Upstream@qlogic.com,
	"James E.J. Bottomley" <jejb@linux.vnet.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	linux-kernel@vger.kernel.org
Subject: [PATCH v4 6/7] scsi: bnx2i: Eliminate duplicate barriers on weakly-ordered archs
Date: Mon, 19 Mar 2018 22:50:06 -0400	[thread overview]
Message-ID: <1521514207-10695-7-git-send-email-okaya@codeaurora.org> (raw)
In-Reply-To: <1521514207-10695-1-git-send-email-okaya@codeaurora.org>

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@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

  parent reply	other threads:[~2018-03-20  2:50 UTC|newest]

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <1521514207-10695-1-git-send-email-okaya@codeaurora.org>
2018-03-20  2:50 ` [PATCH v4 1/7] scsi: hpsa: " Sinan Kaya
2018-03-20 16:51   ` Laurence Oberman
2018-03-20  2:50 ` [PATCH v4 2/7] scsi: megaraid: eliminate " Sinan Kaya
2018-03-20  2:50 ` [PATCH v4 3/7] scsi: dpt_i2o: " Sinan Kaya
2018-03-20 10:23   ` Christoph Hellwig
2018-03-20 12:13     ` okaya
2018-03-20  2:50 ` [PATCH v4 4/7] scsi: lpfc: Eliminate " Sinan Kaya
2018-03-20  2:50 ` [PATCH v4 5/7] scsi: ipr: " Sinan Kaya
2018-05-29 20:45   ` Brian King
2018-03-20  2:50 ` Sinan Kaya [this message]
2018-03-20  2:50 ` [PATCH v4 7/7] scsi: csiostor: " Sinan Kaya

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