From patchwork Mon Feb 26 21:47:07 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Niklas Cassel X-Patchwork-Id: 878153 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netdev-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=axis.com Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 3zqwSn5bKHz9s0x for ; Tue, 27 Feb 2018 08:48:57 +1100 (AEDT) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751919AbeBZVsO (ORCPT ); Mon, 26 Feb 2018 16:48:14 -0500 Received: from bastet.se.axis.com ([195.60.68.11]:54808 "EHLO bastet.se.axis.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750842AbeBZVrZ (ORCPT ); Mon, 26 Feb 2018 16:47:25 -0500 Received: from localhost (localhost [127.0.0.1]) by bastet.se.axis.com (Postfix) with ESMTP id 17F6F1835B; Mon, 26 Feb 2018 22:47:24 +0100 (CET) X-Virus-Scanned: Debian amavisd-new at bastet.se.axis.com Received: from bastet.se.axis.com ([IPv6:::ffff:127.0.0.1]) by localhost (bastet.se.axis.com [::ffff:127.0.0.1]) (amavisd-new, port 10024) with LMTP id wJY3-IuuX3b1; Mon, 26 Feb 2018 22:47:20 +0100 (CET) Received: from boulder02.se.axis.com (boulder02.se.axis.com [10.0.8.16]) by bastet.se.axis.com (Postfix) with ESMTPS id EE31518378; Mon, 26 Feb 2018 22:47:19 +0100 (CET) Received: from boulder02.se.axis.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id D9A941A08E; Mon, 26 Feb 2018 22:47:19 +0100 (CET) Received: from boulder02.se.axis.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id CE8521A08C; Mon, 26 Feb 2018 22:47:19 +0100 (CET) Received: from seth.se.axis.com (unknown [10.0.2.172]) by boulder02.se.axis.com (Postfix) with ESMTP; Mon, 26 Feb 2018 22:47:19 +0100 (CET) Received: from lnxartpec1.se.axis.com (lnxartpec1.se.axis.com [10.88.4.10]) by seth.se.axis.com (Postfix) with ESMTP id C1B556DD; Mon, 26 Feb 2018 22:47:19 +0100 (CET) Received: by lnxartpec1.se.axis.com (Postfix, from userid 20283) id B9B8E401A5; Mon, 26 Feb 2018 22:47:19 +0100 (CET) From: Niklas Cassel To: Giuseppe Cavallaro , Alexandre Torgue Cc: Jose.Abreu@synopsys.com, pavel@ucw.cz, Niklas Cassel , netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH net-next 2/4] net: stmmac: use correct barrier between coherent memory and MMIO Date: Mon, 26 Feb 2018 22:47:07 +0100 Message-Id: <20180226214709.4359-3-niklas.cassel@axis.com> X-Mailer: git-send-email 2.14.2 In-Reply-To: <20180226214709.4359-1-niklas.cassel@axis.com> References: <20180226214709.4359-1-niklas.cassel@axis.com> X-TM-AS-GCONF: 00 Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org The last memory barrier in stmmac_xmit()/stmmac_tso_xmit() is placed between a coherent memory write and a MMIO write: The own bit is written in First Desc (TSO: MSS desc or First Desc). The DMA engine is started by a write to the tx desc tail pointer/ enable dma transmission register, i.e. a MMIO write. This barrier cannot be a simple dma_wmb(), since a dma_wmb() is only used to guarantee the ordering, with respect to other writes, to cache coherent DMA memory. To guarantee that the cache coherent memory writes have completed before we attempt to write to the cache incoherent MMIO region, we need to use the more heavyweight barrier wmb(). Signed-off-by: Niklas Cassel --- drivers/net/ethernet/stmicro/stmmac/stmmac_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c index 3b5e7b06e796..6dd04f237b2a 100644 --- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c +++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c @@ -2997,7 +2997,7 @@ static netdev_tx_t stmmac_tso_xmit(struct sk_buff *skb, struct net_device *dev) * descriptor and then barrier is needed to make sure that * all is coherent before granting the DMA engine. */ - dma_wmb(); + wmb(); if (netif_msg_pktdata(priv)) { pr_info("%s: curr=%d dirty=%d f=%d, e=%d, f_p=%p, nfrags %d\n", @@ -3221,7 +3221,7 @@ static netdev_tx_t stmmac_xmit(struct sk_buff *skb, struct net_device *dev) * descriptor and then barrier is needed to make sure that * all is coherent before granting the DMA engine. */ - dma_wmb(); + wmb(); } netdev_tx_sent_queue(netdev_get_tx_queue(dev, queue), skb->len);