i.MX6 PCI-E LAN MTU size

[shichinhuang]

Hi,

We are debugging an issue like below link,

https://community.nxp.com/thread/321964

We need set MTU=500 (original default value is 1500) for LAN output packet normlly work or it cannot send any output packet.

It seems that the issue of above linked still exist in the kernel.(Linux YOCTO  version 4.9.88-imx_4.9.88_2.0.0_ga+g159b147)

Do you have any updated about the issue?

Thanks!

Sincerely,

Shichin

[jose_oga]

Hello shichinhuang‌

I've just had the same problem. fixed compiling the kernel with the attached patch. Using mainline RT6169 driver.

Let us know if this works.

[shichinhuang]

Hi Jose,

Thank you very much to share the patch.

We will try the patch and test it again.

Thanks!

[jose_oga]

Hello shichinhuang‌

Just wondering, any luck?

Regards,

[shichinhuang]

Hi Jose,

We are working with Realtek about how to implement the patch in the driver.

Thank you for your help!

[b36401]

We have no updates regarding such issue.
Sorry for the inconvenience.

[shichinhuang]

Hi Victor,

Could you help to tell me if the issue was caused by SOC hardware or Linux kernel driver ?

Thanks!

Shichin

[b36401]

In i.MX6 series we have known issue that theoretical maximum performance of gigabit ethernet is only 470 Mbps not 1000 Mbps.
And in real applications the performance is even a bit less than 470 Mbps.
Please note that i.MX series are more multimedia than networking processors.

[shichinhuang]

Hi Victor,

Thanks for your reply.

But the issue is not relevant to transfer speed.

The issue is MTU need reduce from 1500 (ethernet deafult) to 500 for PCI-e LAN normally work on i.MX6.

If we use default value 1500, the PCI-e LAN cannot work. 

[shichinhuang]

Hi Victor,

Thanks for your answer.

For this issue, I would like to what 's the root cause of the MTU size issue on i.MX6 ? Is it related to i.MX6 hardware or kernel issue?

Besides MTU issue, is there any concern of desing PCI-E giga LAN on i.MX6DualLite platform? Because we need design PCI-E giga LAN in the product.

Thanks!

Shichin

[Abi__1289]

Hi shichin,

Did you found the Root cause of having Low MTU size for the IMX6 Chipsets , We are also facing the same issue for the imx6q Chip with linux 5.4 version . Did you applied the patch for working out the rt6189 driver. 

Would be really helpful for response .

Thankyou 

Abhishek