ethernet low performance with imx.6 connected to gigabit ethernet switch

[reinholdfrederi]

Hi,

I use Linux 3.0.35_4.1.0 to imx.6  quad core (Congatec-qmx6) and PHY KSZ9021.Module is connected to Marvell 88E6176 Gigabit Ethernet switch via RMII.

Tests are realized with iperf.

Step1: PC1 to PC2 via switch

PC1 <----> Port2 | Switch Gigabit | Port3 <-----> PC2 : 998 Mbits/s

5 tests complete

Step2: PC1 to Imx-6 without switch

PC1 <----> Imx-6 : 490 Mbits/s

5 tests complete

Step3: PC1 to Imx-6 via switch

PC1 <----> Port2 | Switch Gigabit | Port3 <-----> Imx-6 : 205 Mbits/s

First test is complete.

Second test ethernet communication frezzing.

The ethernet switch works properly with 2 PC's at 998 Mbits/s.

A patch already exist to fix this behavior in Linux drivers (FEC ?) ?

Thanks for your response.

[alxdc]

Hi,

could you tell me which module version do you have and which u-boot and kernel patch level? I would recommend you to use the latest one.

thanks,

alex.

[reinholdfrederi]

"Step2: PC1 to Imx-6 without switch

PC1 <----> Imx-6 : 490 Mbits/s

5 tests complete"

=> it's performance of errata number: ERR004512

"Step3: PC1 to Imx-6 via switch

PC1 <----> Port2 | Switch Gigabit | Port3 <-----> Imx-6 : 205 Mbits/s

First test is complete.

Second test ethernet communication frezzing."

Performance in step3  is not equal to step2.

Partially resolved:

The flow of control has been activated (Marvell Switch Hardware configuration) and now the performance is equal to the errata for the linux kernel 3.0.35 kernel but not for 3.10.17.

Kernel 3.0.35: PC to IMX6: 460 Mbit/s

Kernel 3.10.17: PC to IMX6: 280 Mbit/s

[SergioSolis]

Please take a look at the following errata for the i.MX6

http://cache.freescale.com/files/32bit/doc/errata/IMX6DQCE.pdf

errata number: ERR004512

It explains about the gigabit ethernet limitation of the i.MX6

[reinholdfrederi]

"Step2: PC1 to Imx-6 without switch

PC1 <----> Imx-6 : 490 Mbits/s

5 tests complete"

=> it's performance of errata number: ERR004512

"Step3: PC1 to Imx-6 via switch

PC1 <----> Port2 | Switch Gigabit | Port3 <-----> Imx-6 : 205 Mbits/s

First test is complete.

Second test ethernet communication frezzing."

Performance in step3  is not equal to step2.