From: Joel Stanley joel@jms.id.au
[ Upstream commit 6fd45e79e8b93b8d22fb8fe22c32fbad7e9190bd ]
The AST2600 when using the i210 NIC over NC-SI has been observed to produce incorrect checksum results with specific MTU values. This was first observed when sending data across a long distance set of networks.
On a local network, the following test was performed using a 1MB file of random data.
On the receiver run this script:
#!/bin/bash while [ 1 ]; do # Zero the stats nstat -r > /dev/null nc -l 9899 > test-file # Check for checksum errors TcpInCsumErrors=$(nstat | grep TcpInCsumErrors) if [ -z "$TcpInCsumErrors" ]; then echo No TcpInCsumErrors else echo TcpInCsumErrors = $TcpInCsumErrors fi done
On an AST2600 system:
# nc <IP of receiver host> 9899 < test-file
The test was repeated with various MTU values:
# ip link set mtu 1410 dev eth0
The observed results:
1500 - good 1434 - bad 1400 - good 1410 - bad 1420 - good
The test was repeated after disabling tx checksumming:
# ethtool -K eth0 tx-checksumming off
And all MTU values tested resulted in transfers without error.
An issue with the driver cannot be ruled out, however there has been no bug discovered so far.
David has done the work to take the original bug report of slow data transfer between long distance connections and triaged it down to this test case.
The vendor suspects this this is a hardware issue when using NC-SI. The fixes line refers to the patch that introduced AST2600 support.
Reported-by: David Wilder wilder@us.ibm.com Reviewed-by: Dylan Hung dylan_hung@aspeedtech.com Signed-off-by: Joel Stanley joel@jms.id.au Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/net/ethernet/faraday/ftgmac100.c | 5 +++++ 1 file changed, 5 insertions(+)
diff --git a/drivers/net/ethernet/faraday/ftgmac100.c b/drivers/net/ethernet/faraday/ftgmac100.c index caf48023f8ea..5231818943c6 100644 --- a/drivers/net/ethernet/faraday/ftgmac100.c +++ b/drivers/net/ethernet/faraday/ftgmac100.c @@ -1928,6 +1928,11 @@ static int ftgmac100_probe(struct platform_device *pdev) /* AST2400 doesn't have working HW checksum generation */ if (np && (of_device_is_compatible(np, "aspeed,ast2400-mac"))) netdev->hw_features &= ~NETIF_F_HW_CSUM; + + /* AST2600 tx checksum with NCSI is broken */ + if (priv->use_ncsi && of_device_is_compatible(np, "aspeed,ast2600-mac")) + netdev->hw_features &= ~NETIF_F_HW_CSUM; + if (np && of_get_property(np, "no-hw-checksum", NULL)) netdev->hw_features &= ~(NETIF_F_HW_CSUM | NETIF_F_RXCSUM); netdev->features |= netdev->hw_features;