From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sinan Kaya Subject: [PATCH REPOST v4 6/7] ixgbevf: eliminate duplicate barriers on weakly-ordered archs Date: Wed, 21 Mar 2018 14:56:10 -0400 Message-ID: <1521658572-26354-7-git-send-email-okaya@codeaurora.org> References: <1521658572-26354-1-git-send-email-okaya@codeaurora.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit 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 To: jeffrey.t.kirsher@intel.com Return-path: In-Reply-To: <1521658572-26354-1-git-send-email-okaya@codeaurora.org> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Code includes wmb() followed by writel() in multiple places. 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: Alexander Duyck --- drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c index 6bf778a..774b2a6 100644 --- a/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c +++ b/drivers/net/ethernet/intel/ixgbevf/ixgbevf_main.c @@ -659,7 +659,7 @@ static void ixgbevf_alloc_rx_buffers(struct ixgbevf_ring *rx_ring, * such as IA-64). */ wmb(); - writel(i, rx_ring->tail); + writel_relaxed(i, rx_ring->tail); } } @@ -3644,7 +3644,7 @@ static void ixgbevf_tx_map(struct ixgbevf_ring *tx_ring, tx_ring->next_to_use = i; /* notify HW of packet */ - writel(i, tx_ring->tail); + writel_relaxed(i, tx_ring->tail); return; dma_error: -- 2.7.4