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From: Yanglong Wu <yanglong.wu@intel.com>
To: dev@dpdk.org
Cc: qi.z.zhang@intel.com, jingjing.wu@intel.com,
	Yanglong Wu <yanglong.wu@intel.com>
Subject: [dpdk-dev] [PATCH v2] net/ixgbe: fix TDH register setting issue
Date: Tue, 20 Nov 2018 13:59:21 +0800	[thread overview]
Message-ID: <20181120055921.8209-1-yanglong.wu@intel.com> (raw)
In-Reply-To: <20181116023220.114517-1-yanglong.wu@intel.com>

The only time that software should write to the TDH register
is after a reset (hardware reset or CTRL.RST) and
before enabling the transmit function (TXDCTL.ENABLE).
If software were to write to this register while the transmit
function was enabled, the on-chip descriptor buffers might
be invalidated and the hardware could become confused.

cc stable@dpdk.org
Signed-off-by: Yanglong Wu <yanglong.wu@intel.com>
---
v2:
change fix commit
---
 drivers/net/ixgbe/ixgbe_rxtx.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ixgbe/ixgbe_rxtx.c b/drivers/net/ixgbe/ixgbe_rxtx.c
index 2f0262ae1..ddc7efa87 100644
--- a/drivers/net/ixgbe/ixgbe_rxtx.c
+++ b/drivers/net/ixgbe/ixgbe_rxtx.c
@@ -5264,6 +5264,7 @@ ixgbe_dev_tx_queue_start(struct rte_eth_dev *dev, uint16_t tx_queue_id)
 	hw = IXGBE_DEV_PRIVATE_TO_HW(dev->data->dev_private);
 
 	txq = dev->data->tx_queues[tx_queue_id];
+	IXGBE_WRITE_REG(hw, IXGBE_TDH(txq->reg_idx), 0);
 	txdctl = IXGBE_READ_REG(hw, IXGBE_TXDCTL(txq->reg_idx));
 	txdctl |= IXGBE_TXDCTL_ENABLE;
 	IXGBE_WRITE_REG(hw, IXGBE_TXDCTL(txq->reg_idx), txdctl);
@@ -5281,7 +5282,6 @@ ixgbe_dev_tx_queue_start(struct rte_eth_dev *dev, uint16_t tx_queue_id)
 				tx_queue_id);
 	}
 	rte_wmb();
-	IXGBE_WRITE_REG(hw, IXGBE_TDH(txq->reg_idx), 0);
 	IXGBE_WRITE_REG(hw, IXGBE_TDT(txq->reg_idx), 0);
 	dev->data->tx_queue_state[tx_queue_id] = RTE_ETH_QUEUE_STATE_STARTED;
 
-- 
2.11.0

  parent reply	other threads:[~2018-11-20  6:13 UTC|newest]

Thread overview: 6+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-11-16  2:32 [dpdk-dev] [PATCH] " Yanglong Wu
2018-11-16 19:51 ` Zhang, Qi Z
2018-11-20  2:11   ` Wu, Yanglong
2018-11-20  6:02     ` Zhang, Qi Z
2018-11-20  5:59 ` Yanglong Wu [this message]
2018-11-20 19:49   ` [dpdk-dev] [PATCH v2] " Zhang, Qi Z

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