From: Sinan Kaya <okaya@codeaurora.org> To: netdev@vger.kernel.org, timur@codeaurora.org, sulrich@codeaurora.org Cc: linux-arm-msm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Sinan Kaya <okaya@codeaurora.org>, Harish Patil <harish.patil@cavium.com>, Manish Chopra <manish.chopra@cavium.com>, Dept-GELinuxNICDev@cavium.com, linux-kernel@vger.kernel.org Subject: [PATCH v6 5/6] net: qlge: Eliminate duplicate barriers on weakly-ordered archs Date: Fri, 23 Mar 2018 18:23:10 -0400 [thread overview] Message-ID: <1521843791-21201-6-git-send-email-okaya@codeaurora.org> (raw) In-Reply-To: <1521843791-21201-1-git-send-email-okaya@codeaurora.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. 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 <okaya@codeaurora.org> --- drivers/net/ethernet/qlogic/qlge/qlge.h | 16 ++++++++++++++++ drivers/net/ethernet/qlogic/qlge/qlge_main.c | 3 ++- 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/qlogic/qlge/qlge.h b/drivers/net/ethernet/qlogic/qlge/qlge.h index 84ac50f..3e71b65 100644 --- a/drivers/net/ethernet/qlogic/qlge/qlge.h +++ b/drivers/net/ethernet/qlogic/qlge/qlge.h @@ -2185,6 +2185,22 @@ 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); +} + +/* * 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..8293c202 100644 --- a/drivers/net/ethernet/qlogic/qlge/qlge_main.c +++ b/drivers/net/ethernet/qlogic/qlge/qlge_main.c @@ -2700,7 +2700,8 @@ 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); + mmiowb(); netif_printk(qdev, tx_queued, KERN_DEBUG, qdev->ndev, "tx queued, slot %d, len %d\n", tx_ring->prod_idx, skb->len); -- 2.7.4
WARNING: multiple messages have this Message-ID (diff)
From: okaya@codeaurora.org (Sinan Kaya) To: linux-arm-kernel@lists.infradead.org Subject: [PATCH v6 5/6] net: qlge: Eliminate duplicate barriers on weakly-ordered archs Date: Fri, 23 Mar 2018 18:23:10 -0400 [thread overview] Message-ID: <1521843791-21201-6-git-send-email-okaya@codeaurora.org> (raw) In-Reply-To: <1521843791-21201-1-git-send-email-okaya@codeaurora.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. 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 <okaya@codeaurora.org> --- drivers/net/ethernet/qlogic/qlge/qlge.h | 16 ++++++++++++++++ drivers/net/ethernet/qlogic/qlge/qlge_main.c | 3 ++- 2 files changed, 18 insertions(+), 1 deletion(-) diff --git a/drivers/net/ethernet/qlogic/qlge/qlge.h b/drivers/net/ethernet/qlogic/qlge/qlge.h index 84ac50f..3e71b65 100644 --- a/drivers/net/ethernet/qlogic/qlge/qlge.h +++ b/drivers/net/ethernet/qlogic/qlge/qlge.h @@ -2185,6 +2185,22 @@ 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); +} + +/* * 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..8293c202 100644 --- a/drivers/net/ethernet/qlogic/qlge/qlge_main.c +++ b/drivers/net/ethernet/qlogic/qlge/qlge_main.c @@ -2700,7 +2700,8 @@ 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); + mmiowb(); netif_printk(qdev, tx_queued, KERN_DEBUG, qdev->ndev, "tx queued, slot %d, len %d\n", tx_ring->prod_idx, skb->len); -- 2.7.4
next prev parent reply other threads:[~2018-03-23 22:23 UTC|newest] Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top 2018-03-23 22:23 [PATCH v6 0/6] netdev: Eliminate duplicate barriers on weakly-ordered archs Sinan Kaya 2018-03-23 22:23 ` Sinan Kaya 2018-03-23 22:23 ` [PATCH v6 1/6] net: qla3xxx: " Sinan Kaya 2018-03-23 22:23 ` Sinan Kaya 2018-03-23 22:23 ` [PATCH v6 2/6] qlcnic: " Sinan Kaya 2018-03-23 22:23 ` Sinan Kaya 2018-03-23 22:23 ` Sinan Kaya 2018-03-23 22:23 ` [PATCH v6 3/6] bnx2x: Replace doorbell barrier() with wmb() Sinan Kaya 2018-03-23 22:23 ` Sinan Kaya 2018-03-23 22:23 ` Sinan Kaya 2018-03-23 22:23 ` [PATCH v6 4/6] bnx2x: Eliminate duplicate barriers on weakly-ordered archs Sinan Kaya 2018-03-23 22:23 ` Sinan Kaya 2018-03-23 22:23 ` Sinan Kaya [this message] 2018-03-23 22:23 ` [PATCH v6 5/6] net: qlge: " Sinan Kaya 2018-03-23 22:23 ` [PATCH v6 6/6] bnxt_en: " Sinan Kaya 2018-03-23 22:23 ` Sinan Kaya 2018-03-23 22:36 ` Michael Chan 2018-03-23 22:36 ` Michael Chan 2018-03-24 4:02 ` Sinan Kaya 2018-03-24 4:02 ` Sinan Kaya
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