From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752195AbeCWSXm (ORCPT ); Fri, 23 Mar 2018 14:23:42 -0400 Received: from smtp.codeaurora.org ([198.145.29.96]:40736 "EHLO smtp.codeaurora.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751812AbeCWSVa (ORCPT ); Fri, 23 Mar 2018 14:21:30 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 0015D60F61 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 Cc: netdev@vger.kernel.org, timur@codeaurora.org, sulrich@codeaurora.org, linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sinan Kaya , intel-wired-lan@lists.osuosl.org, linux-kernel@vger.kernel.org Subject: [PATCH v6 3/7] igbvf: eliminate duplicate barriers on weakly-ordered archs Date: Fri, 23 Mar 2018 14:21:13 -0400 Message-Id: <1521829277-9398-4-git-send-email-okaya@codeaurora.org> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1521829277-9398-1-git-send-email-okaya@codeaurora.org> References: <1521829277-9398-1-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 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/igbvf/netdev.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/intel/igbvf/netdev.c b/drivers/net/ethernet/intel/igbvf/netdev.c index fa07876..6dfd3dc 100644 --- a/drivers/net/ethernet/intel/igbvf/netdev.c +++ b/drivers/net/ethernet/intel/igbvf/netdev.c @@ -252,7 +252,12 @@ static void igbvf_alloc_rx_buffers(struct igbvf_ring *rx_ring, * such as IA-64). */ wmb(); - writel(i, adapter->hw.hw_addr + rx_ring->tail); + writel_relaxed(i, adapter->hw.hw_addr + rx_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 + */ + mmiowb(); } } @@ -2298,7 +2303,7 @@ static inline void igbvf_tx_queue_adv(struct igbvf_adapter *adapter, tx_ring->buffer_info[first].next_to_watch = tx_desc; tx_ring->next_to_use = i; - writel(i, adapter->hw.hw_addr + tx_ring->tail); + writel_relaxed(i, adapter->hw.hw_addr + 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 */ -- 2.7.4