From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752446AbeCTCus (ORCPT ); Mon, 19 Mar 2018 22:50:48 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:35940 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752230AbeCTCuh (ORCPT ); Mon, 19 Mar 2018 22:50:37 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 647D560F92 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=okaya@codeaurora.org From: Sinan Kaya 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 , "James E.J. Bottomley" , "Martin K. Petersen" , Varun Prakash , Peter Senna Tschudin , Romain Perier , linux-kernel@vger.kernel.org Subject: [PATCH v4 7/7] scsi: csiostor: Eliminate duplicate barriers on weakly-ordered archs Date: Mon, 19 Mar 2018 22:50:07 -0400 Message-Id: <1521514207-10695-8-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521514207-10695-1-git-send-email-okaya@codeaurora.org> References: <1521514207-10695-1-git-send-email-okaya@codeaurora.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.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. Create a new wrapper function with relaxed write operator. Use the new wrapper when a write is following a barrier(). Signed-off-by: Sinan Kaya --- drivers/scsi/csiostor/csio_hw.h | 4 ++++ drivers/scsi/csiostor/csio_wr.c | 2 +- 2 files changed, 5 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/csiostor/csio_hw.h b/drivers/scsi/csiostor/csio_hw.h index 30f5f52..9fd8b00 100644 --- a/drivers/scsi/csiostor/csio_hw.h +++ b/drivers/scsi/csiostor/csio_hw.h @@ -512,6 +512,10 @@ struct csio_hw { csio_reg((_h)->regstart, (_r))) #define csio_wr_reg16(_h, _v, _r) writew((_v), \ csio_reg((_h)->regstart, (_r))) + +#define csio_wr_reg32_relaxed(_h, _v, _r) \ + writel_relaxed((_v), csio_reg((_h)->regstart, (_r))) + #define csio_wr_reg32(_h, _v, _r) writel((_v), \ csio_reg((_h)->regstart, (_r))) #define csio_wr_reg64(_h, _v, _r) writeq((_v), \ diff --git a/drivers/scsi/csiostor/csio_wr.c b/drivers/scsi/csiostor/csio_wr.c index c0a1778..db26222 100644 --- a/drivers/scsi/csiostor/csio_wr.c +++ b/drivers/scsi/csiostor/csio_wr.c @@ -984,7 +984,7 @@ csio_wr_issue(struct csio_hw *hw, int qidx, bool prio) wmb(); /* Ring SGE Doorbell writing q->pidx into it */ - csio_wr_reg32(hw, DBPRIO_V(prio) | QID_V(q->un.eq.physeqid) | + csio_wr_reg32_relaxed(hw, DBPRIO_V(prio) | QID_V(q->un.eq.physeqid) | PIDX_T5_V(q->inc_idx) | DBTYPE_F, MYPF_REG(SGE_PF_KDOORBELL_A)); q->inc_idx = 0; -- 2.7.4