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 v4 14/17] net: qlge: Eliminate duplicate barriers on weakly-ordered archs
Date: Mon, 19 Mar 2018 22:42:29 -0400 [thread overview]
Message-ID: <1521513753-7325-15-git-send-email-okaya@codeaurora.org> (raw)
In-Reply-To: <1521513753-7325-1-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 | 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);
--
2.7.4
next prev parent reply other threads:[~2018-03-20 2:42 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-03-20 2:42 [PATCH v4 00/17] netdev: Eliminate duplicate barriers on weakly-ordered archs Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 01/17] i40e/i40evf: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 02/17] ixgbe: eliminate " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 03/17] igbvf: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 04/17] igb: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 05/17] ixgbevf: keep writel() closer to wmb() Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 06/17] ixgbevf: eliminate duplicate barriers on weakly-ordered archs Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 07/17] fm10k: Eliminate " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 08/17] drivers: net: cxgb: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 09/17] net: qla3xxx: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 10/17] qlcnic: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 11/17] bnx2x: " Sinan Kaya
2018-03-22 10:10 ` Kalluru, Sudarsana
2018-03-20 2:42 ` [PATCH v4 12/17] net: cxgb4/cxgb4vf: " Sinan Kaya
2018-03-21 23:03 ` Casey Leedom
2018-03-22 0:00 ` okaya
2018-03-20 2:42 ` [PATCH v4 13/17] net: cxgb3: " Sinan Kaya
2018-03-20 2:42 ` Sinan Kaya [this message]
2018-03-20 2:42 ` [PATCH v4 15/17] bnxt_en: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 16/17] qed/qede: " Sinan Kaya
2018-03-20 2:42 ` [PATCH v4 17/17] net: ena: " Sinan Kaya
2018-03-25 12:06 ` Belgazal, Netanel
2018-03-25 13:33 ` okaya
2018-03-21 15:56 ` [PATCH v4 00/17] netdev: " David Miller
2018-03-21 19:06 ` Sinan Kaya
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