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e1000: Use dma_wmb() instead of wmb() before doorbell writes

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e1000 writes to doorbells to post transmit descriptors and fill the
receive ring. After writing descriptors to memory but before
writing to doorbells, use dma_wmb() rather than wmb(). wmb() is more
heavyweight than necessary for a device to see descriptor writes.

On x86, this avoids SFENCEs before doorbell writes in both the
Tx and Rx paths. On ARM, this converts DSB ST -> DMB OSHST.

Tested: 82576EB / x86; QEMU (qemu emulates an 8257x)

Signed-off-by: Venkatesh Srinivas <venkateshs@google.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
This commit is contained in:
Venkatesh Srinivas
2019-06-10 14:27:50 -07:00
committed by Jeff Kirsher
parent b97c0b521a
commit 583cf7be75
1 changed files with 3 additions and 3 deletions
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6
drivers/net/ethernet/intel/e1000/e1000_main.c
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@@ -3019,7 +3019,7 @@ static void e1000_tx_queue(struct e1000_adapter *adapter,
* applicable for weak-ordered memory model archs,
* such as IA-64).
*/
wmb();
dma_wmb();
tx_ring->next_to_use = i;
}
@@ -4540,7 +4540,7 @@ e1000_alloc_jumbo_rx_buffers(struct e1000_adapter *adapter,
* applicable for weak-ordered memory model archs,
* such as IA-64).
*/
wmb();
dma_wmb();
writel(i, adapter->hw.hw_addr + rx_ring->rdt);
}
}
@@ -4655,7 +4655,7 @@ static void e1000_alloc_rx_buffers(struct e1000_adapter *adapter,
* applicable for weak-ordered memory model archs,
* such as IA-64).
*/
wmb();
dma_wmb();
writel(i, hw->hw_addr + rx_ring->rdt);
}
}