From patchwork Fri Mar 23 18:52:58 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sinan Kaya X-Patchwork-Id: 10305401 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 CD437605F7 for ; Fri, 23 Mar 2018 18:57:35 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id BE8A228B76 for ; Fri, 23 Mar 2018 18:57:35 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id B2F1028D85; Fri, 23 Mar 2018 18:57:35 +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=-1.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID autolearn=ham version=3.3.1 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 33D8A28D79 for ; Fri, 23 Mar 2018 18:57:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-Id:Date:Subject:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=75Gus4rmb8qgLMuYCkMcad5z6D6Z4ySuzySGZTROTo8=; b=snApY7E0argCS5 5Hbxow7vHVZzoBpvrOHjxGukdcMPqVGeekbTHtBKK9+GI5ddM3pj+9Bn48hp+mHfYqbARvk71cUXM WfH+ZH91LjKf5Rrq12+mxMUCxsq/vWpNgJO4LNExWL6Jo0k8u3jVJrLLWszqNCPk8XgzpyJqU9/aN L0N+egFa0TfvMF4kEMXnzjlJP8MgtHKUS4IGCHRh8YA82JCnekujRfn1skVamVYOTKjRXECbvfuef /m93DtNDkGvSP/i2NIQlXXcNNFsyNqrFV0Z+Ep+pG5P0LlurhZiMwbnkIsWLvZEZP6pXq1KB0iTHN qFatEcLSKaG6Sc2a9g1A==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1ezRsR-0000ok-3A; Fri, 23 Mar 2018 18:57:23 +0000 Received: from smtp.codeaurora.org ([198.145.29.96]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1ezRod-0005md-3z for linux-arm-kernel@lists.infradead.org; Fri, 23 Mar 2018 18:53:40 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id 601C160C66; Fri, 23 Mar 2018 18:53:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1521831193; bh=WJStVcJks8p7B/WOhvD2VsqofnoOONsyrTwt5Cl2tXk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LvuF0ck0b1GYRKsNhAfLrJ06e/Dxayd7ZHVUF46M8AfN9Q7COxs3GWW3LL5gd8rgS mgXP6DNG5UDUZgRJ2WQCX+RuOP5/uzNPaZKBVw4YNNgPceA44bL1EIWUZsqj6VyrEs 1QeAdgsQXWTMy0mQgC7XWgUB6oEpuJj46f/lV7Fo= 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 D2BDD60F90; Fri, 23 Mar 2018 18:53:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1521831191; bh=WJStVcJks8p7B/WOhvD2VsqofnoOONsyrTwt5Cl2tXk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=j0W0G0hpJ5sYC5+8AoNTq+T2WgPT0qzQ/raOhmXnS0isVNf1sxT/EwBFanLjeKqQG IB1MZxuA34cPjHlceG/MI4uAhPwI+M+4bTUzDhEJv6qjnTZJ/xBBRjbvwMpCtGM02M uEZANaxE+kuqWunoca38JYZDpKgxvUqwOXFZxGOs= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org D2BDD60F90 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: jeffrey.t.kirsher@intel.com Subject: [PATCH v7 5/7] fm10k: Eliminate duplicate barriers on weakly-ordered archs Date: Fri, 23 Mar 2018 14:52:58 -0400 Message-Id: <1521831180-25014-6-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521831180-25014-1-git-send-email-okaya@codeaurora.org> References: <1521831180-25014-1-git-send-email-okaya@codeaurora.org> MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20180323_115328_042380_6A16ECCE X-CRM114-Status: GOOD ( 12.46 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: sulrich@codeaurora.org, netdev@vger.kernel.org, timur@codeaurora.org, linux-kernel@vger.kernel.org, Sinan Kaya , intel-wired-lan@lists.osuosl.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.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 --- drivers/net/ethernet/intel/fm10k/fm10k_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/intel/fm10k/fm10k_main.c b/drivers/net/ethernet/intel/fm10k/fm10k_main.c index 409554d..bb94f04 100644 --- a/drivers/net/ethernet/intel/fm10k/fm10k_main.c +++ b/drivers/net/ethernet/intel/fm10k/fm10k_main.c @@ -180,7 +180,7 @@ void fm10k_alloc_rx_buffers(struct fm10k_ring *rx_ring, u16 cleaned_count) wmb(); /* notify hardware of new descriptors */ - writel(i, rx_ring->tail); + writel_relaxed(i, rx_ring->tail); } } @@ -1055,7 +1055,7 @@ static void fm10k_tx_map(struct fm10k_ring *tx_ring, /* notify HW of packet */ if (netif_xmit_stopped(txring_txq(tx_ring)) || !skb->xmit_more) { - writel(i, tx_ring->tail); + writel_relaxed(i, tx_ring->tail); /* we need this if more than one processor can write to our tail * at a time, it synchronizes IO on IA64/Altix systems