imx6ull tcp checksum

[vladimirchernin]

hi!

We have a board based on imx6ull with 2 RMIIs connected and running Linux kernel 4.9

We see a problem after MTU size is over 1100 bytes TCP stack checksum is zero and its start retransmissions

and connection very slow.

By the default, the checksum is hardware offload is on.if we set it off by ethtool and it's calculated on CPU

TCP checksum calculated properly but CPU load is high.

Its seem like problem in NXPs BSP 

please help us to solve the problem!

Regards

Vladimir

[vladimirchernin]

hi!

you need to connect via RMII Mac to Mac mode and make TCP connections with different MTU sizes 

[Yuri]

Hello,

  REF_CLK of 50MHz is needed for RMII. Is it provided / configured correctly ?

Please check.

Regards,

Yuri.

[vladimirchernin]

hi!

in my dts it defined like this

&fec2 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_enet2>;
phy-mode = "rmii";
status = "okay";
fixed-link {
speed = <100>;
full-duplex;
};
};

&fec1 {
pinctrl-names = "default";
pinctrl-0 = <&pinctrl_enet1>;
phy-mode = "rmii";
status = "okay";
fixed-link {
speed = <100>;
full-duplex;
};
};

and clock is 50MHZ we don't change anything regarding the clock

it is working but not calculates TCP CRC and its gets 0 value in the packet depend on MTU size

Regards

Vladimir

[Yuri]

Hello,

Is it possible to look at the MAC-to-MAC connection scheme?

Is it as shown FIGURE 1 of the RMII specs? 

http://ebook.pldworld.com/_eBook/-Telecommunications,Networks-/TCPIP/RMII/rmii_rev12.pdf   

Regards,

Yuri.

[vladimirchernin]

hi!

please see schematic

RMII works and it has a problem only from 1200 MTU size  and more

when imx6ull calculate CRC for TCP stack

its looks like BSP bug?   

thanks

vladimir

[Yuri]

Hello,

  Do You use fixed-link? 

Is NXP BSP applied (without custom modifications)?

Is it possible to enable the pause frame to check performance issue(s)? 

Regards,

Yuri.

[Yuri]

Hello,

  Let me know how can I reproduce the issue oni.MX 6ULL EVK ?

Regards,

Yuri.

[vladimirchernin]

Yuri

pls see next URLs

http://lists.infradead.org/pipermail/linux-arm-kernel/2014-July/273243.html

http://lists.infradead.org/pipermail/linux-arm-kernel/2014-July/272899.html