From patchwork Fri Mar 16 16:16:31 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sinan Kaya X-Patchwork-Id: 10288989 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id CA99D601BE for ; Fri, 16 Mar 2018 16:17:46 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B874128FB6 for ; Fri, 16 Mar 2018 16:17:46 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id ACCBB28FB8; Fri, 16 Mar 2018 16:17:46 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_HI,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E014428FB6 for ; Fri, 16 Mar 2018 16:17:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934795AbeCPQR0 (ORCPT ); Fri, 16 Mar 2018 12:17:26 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:40208 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934786AbeCPQRS (ORCPT ); Fri, 16 Mar 2018 12:17:18 -0400 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id D13B660F91; Fri, 16 Mar 2018 16:17:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1521217037; bh=YmiBiHfBFxB/QX4t7jV96OH54ymLfBQUTuIkFE7KxYY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S4hbEwb6wmQTkdupZATjmWyjOyoP9KLWhDSRWN/Vfx3gmbQha9G7EZt4GBgvAtB6U RATkphIiF6eVSI4bvJBgiNAcXe89a1JAW2CE7MJz1jLNIajMk29YgBPkJCqMjWpV9u F3dFp/lel6O3Qh4yagaS3orNvfy5mkr2cHHHOlOE= Received: from drakthul.qualcomm.com (global_nat1_iad_fw.qualcomm.com [129.46.232.65]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: okaya@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id E093D60F94; Fri, 16 Mar 2018 16:17:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1521217037; bh=YmiBiHfBFxB/QX4t7jV96OH54ymLfBQUTuIkFE7KxYY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=S4hbEwb6wmQTkdupZATjmWyjOyoP9KLWhDSRWN/Vfx3gmbQha9G7EZt4GBgvAtB6U RATkphIiF6eVSI4bvJBgiNAcXe89a1JAW2CE7MJz1jLNIajMk29YgBPkJCqMjWpV9u F3dFp/lel6O3Qh4yagaS3orNvfy5mkr2cHHHOlOE= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org E093D60F94 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: netdev@vger.kernel.org, timur@codeaurora.org, sulrich@codeaurora.org Cc: linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sinan Kaya , Steve Wise , Doug Ledford , Jason Gunthorpe , linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 18/18] infiniband: cxgb4: Eliminate duplicate barriers on weakly-ordered archs Date: Fri, 16 Mar 2018 12:16:31 -0400 Message-Id: <1521216991-28706-19-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521216991-28706-1-git-send-email-okaya@codeaurora.org> References: <1521216991-28706-1-git-send-email-okaya@codeaurora.org> MIME-Version: 1.0 Sender: linux-rdma-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rdma@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP 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. Since code already has an explicit barrier call, changing writel() to writel_relaxed(). Signed-off-by: Sinan Kaya Reviewed-by: Steve Wise --- drivers/infiniband/hw/cxgb4/t4.h | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/infiniband/hw/cxgb4/t4.h b/drivers/infiniband/hw/cxgb4/t4.h index 8369c7c..7a48c9e 100644 --- a/drivers/infiniband/hw/cxgb4/t4.h +++ b/drivers/infiniband/hw/cxgb4/t4.h @@ -477,15 +477,15 @@ static inline void t4_ring_sq_db(struct t4_wq *wq, u16 inc, union t4_wr *wqe) (u64 *)wqe); } else { pr_debug("DB wq->sq.pidx = %d\n", wq->sq.pidx); - writel(PIDX_T5_V(inc) | QID_V(wq->sq.bar2_qid), - wq->sq.bar2_va + SGE_UDB_KDOORBELL); + writel_relaxed(PIDX_T5_V(inc) | QID_V(wq->sq.bar2_qid), + wq->sq.bar2_va + SGE_UDB_KDOORBELL); } /* Flush user doorbell area writes. */ wmb(); return; } - writel(QID_V(wq->sq.qid) | PIDX_V(inc), wq->db); + writel_relaxed(QID_V(wq->sq.qid) | PIDX_V(inc), wq->db); } static inline void t4_ring_rq_db(struct t4_wq *wq, u16 inc, @@ -502,15 +502,15 @@ static inline void t4_ring_rq_db(struct t4_wq *wq, u16 inc, (void *)wqe); } else { pr_debug("DB wq->rq.pidx = %d\n", wq->rq.pidx); - writel(PIDX_T5_V(inc) | QID_V(wq->rq.bar2_qid), - wq->rq.bar2_va + SGE_UDB_KDOORBELL); + writel_relaxed(PIDX_T5_V(inc) | QID_V(wq->rq.bar2_qid), + wq->rq.bar2_va + SGE_UDB_KDOORBELL); } /* Flush user doorbell area writes. */ wmb(); return; } - writel(QID_V(wq->rq.qid) | PIDX_V(inc), wq->db); + writel_relaxed(QID_V(wq->rq.qid) | PIDX_V(inc), wq->db); } static inline int t4_wq_in_error(struct t4_wq *wq)