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Tue, 20 Mar 2018 02:43:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1521513783; bh=sZdCYXegx4QIB6FasQI7rPdIHdDjCxccFKzJmt34JLs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=MLBo6d6ssNwDfQwy8kmytvwulSDwLmF8PXrsID+mBY+kleWm0MdOhc9aiewNO5P/q MUiuW7Qk5lcoZdDhJlkHcR8lQ6qaoJELqQzFMmDaueb3O4AOEXJJ0N7/WfOUKe4Emy GvTnmgvP1QtpiVKXeKK5nZlIlRbScBECLRPEWhnA= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 329EC61153 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 14/17] net: qlge: Eliminate duplicate barriers on weakly-ordered archs Date: Mon, 19 Mar 2018 22:42:29 -0400 Message-Id: <1521513753-7325-15-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_194315_288793_476996CA X-CRM114-Status: GOOD ( 13.25 ) 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: Dept-GELinuxNICDev@cavium.com, linux-arm-msm@vger.kernel.org, linux-kernel@vger.kernel.org, Sinan Kaya , Harish Patil , linux-arm-kernel@lists.infradead.org, Manish Chopra 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. Create a new wrapper function with relaxed write operator. Use the new wrapper when a write is following a wmb(). Signed-off-by: Sinan Kaya --- drivers/net/ethernet/qlogic/qlge/qlge.h | 18 ++++++++++++++++++ drivers/net/ethernet/qlogic/qlge/qlge_main.c | 2 +- 2 files changed, 19 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/qlogic/qlge/qlge.h b/drivers/net/ethernet/qlogic/qlge/qlge.h index 84ac50f..1465986 100644 --- a/drivers/net/ethernet/qlogic/qlge/qlge.h +++ b/drivers/net/ethernet/qlogic/qlge/qlge.h @@ -2185,6 +2185,24 @@ static inline void ql_write_db_reg(u32 val, void __iomem *addr) } /* + * Doorbell Registers: + * Doorbell registers are virtual registers in the PCI memory space. + * The space is allocated by the chip during PCI initialization. The + * device driver finds the doorbell address in BAR 3 in PCI config space. + * The registers are used to control outbound and inbound queues. For + * example, the producer index for an outbound queue. Each queue uses + * 1 4k chunk of memory. The lower half of the space is for outbound + * queues. The upper half is for inbound queues. + * Caller has to guarantee ordering. + */ +static inline void ql_write_db_reg_relaxed(u32 val, void __iomem *addr) +{ + writel_relaxed(val, addr); + mmiowb(); +} + + +/* * Shadow Registers: * Outbound queues have a consumer index that is maintained by the chip. * Inbound queues have a producer index that is maintained by the chip. diff --git a/drivers/net/ethernet/qlogic/qlge/qlge_main.c b/drivers/net/ethernet/qlogic/qlge/qlge_main.c index 50038d9..c222b7c 100644 --- a/drivers/net/ethernet/qlogic/qlge/qlge_main.c +++ b/drivers/net/ethernet/qlogic/qlge/qlge_main.c @@ -2700,7 +2700,7 @@ static netdev_tx_t qlge_send(struct sk_buff *skb, struct net_device *ndev) tx_ring->prod_idx = 0; wmb(); - ql_write_db_reg(tx_ring->prod_idx, tx_ring->prod_idx_db_reg); + ql_write_db_reg_relaxed(tx_ring->prod_idx, tx_ring->prod_idx_db_reg); netif_printk(qdev, tx_queued, KERN_DEBUG, qdev->ndev, "tx queued, slot %d, len %d\n", tx_ring->prod_idx, skb->len);