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alistair23-linux/drivers/net/ethernet/google
Liran Alon c2ae3ce351 net: Google gve: Remove dma_wmb() before ringing doorbell
[ Upstream commit b54ef37b1c ]

Current code use dma_wmb() to ensure Rx/Tx descriptors are visible
to device before writing to doorbell.

However, these dma_wmb() are wrong and unnecessary. Therefore,
they should be removed.

iowrite32be() called from gve_rx_write_doorbell()/gve_tx_put_doorbell()
should guaratee that all previous writes to WB/UC memory is visible to
device before the write done by iowrite32be().

E.g. On ARM64, iowrite32be() calls __iowmb() which expands to dma_wmb()
and only then calls __raw_writel().

Reviewed-by: Si-Wei Liu <si-wei.liu@oracle.com>
Signed-off-by: Liran Alon <liran.alon@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-02-01 09:34:44 +00:00
..
gve net: Google gve: Remove dma_wmb() before ringing doorbell 2020-02-01 09:34:44 +00:00
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