From patchwork Tue Mar 20 02:42:22 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sinan Kaya X-Patchwork-Id: 10296005 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 3F93660385 for ; Tue, 20 Mar 2018 02:45:38 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2F3D32922E for ; Tue, 20 Mar 2018 02:45:38 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 2413729233; Tue, 20 Mar 2018 02:45:38 +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 24D9A2922E for ; Tue, 20 Mar 2018 02:45:37 +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=2txoRrM6bPeU0Y1E34MkWRJ98Xwvs6OWoNkSj450tbA=; b=QJtOCnigm3I/S1 dzoVmTG9DGZC/98f5Z2JEboBGmjktWISZ+UYiCPCa7LTunmAK8XQSCXj2sy2BU4VeiTTG2+iDSpDo s/xJObHm590dnAqD4ZsskIhEMSTfdtiIK/lGUOLPZEojqlT9Op/A5F/akSIEJ6LTBsB3207Di8Hk0 aZtn1n+OZaWoqXqeLlX/aDu8ABzUO/29ylgeRZD6VTi0+SIBGSQBMVdOwcvhwLRwhGpFBFaKpNqkz JsDLa/8kX+ryArOIPigTh/d9d+tHz/EYsNCyHeUR4LlfVeucSXqE6CpUENArwkoazQP0HkA4AalIe EYefWtnLvCTBIEH14mzw==; 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 1ey7HI-00023g-G8; Tue, 20 Mar 2018 02:45:32 +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 1ey7Es-0008Vk-5a for linux-arm-kernel@lists.infradead.org; Tue, 20 Mar 2018 02:43:11 +0000 Received: by smtp.codeaurora.org (Postfix, from userid 1000) id A5E7960F5F; Tue, 20 Mar 2018 02:42:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1521513769; bh=BP2NEOOSikWKnKxDi5MbxXs30YOknO4W7TIZoKbCnPE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=kZ4NSl5X6mxiEzxOPp5ZrtUmpl0Jd5JPkva4/iG4XRjgZAderajgHQHITxAwGGpa6 C0SyHDsaHv+DsEemmP319khc3/9lup+e5qRMP0PNA94LvbVAujl2QdHDu2XBko0jHQ 0B82rz7he8Fhlfz/d+E9qF195GqhTGZaJ1ZVeCI4= 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 691C860FA8; Tue, 20 Mar 2018 02:42:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1521513768; bh=BP2NEOOSikWKnKxDi5MbxXs30YOknO4W7TIZoKbCnPE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MuXejWyqacE6q8OGT6GbtJ2zxGIlec2euZRfBas1hTakOYQV6Xcax10wItOMASNrs Gj+EpVuA/OJHkoVfKuT9H0zPaQlXxD4jbPEAMuMkczXu6etzwfV9cJBNaZy0c7/175 BDamYI1geOWjiP66yR9wpyLIycVYHQV8xF07s/II= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 691C860FA8 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 Subject: [PATCH v4 07/17] fm10k: Eliminate duplicate barriers on weakly-ordered archs Date: Mon, 19 Mar 2018 22:42:22 -0400 Message-Id: <1521513753-7325-8-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521513753-7325-1-git-send-email-okaya@codeaurora.org> References: <1521513753-7325-1-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-20180319_194302_725791_E308F9EE X-CRM114-Status: GOOD ( 12.59 ) 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: linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, Sinan Kaya , intel-wired-lan@lists.osuosl.org, Jeff Kirsher , 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 8e12aae..eebef01 100644 --- a/drivers/net/ethernet/intel/fm10k/fm10k_main.c +++ b/drivers/net/ethernet/intel/fm10k/fm10k_main.c @@ -179,7 +179,7 @@ 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); } } @@ -1054,7 +1054,7 @@ 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