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FEC driver about dual LAN port

Question asked by Jrtiger Lee on Nov 19, 2013
Latest reply on Mar 21, 2014 by Jrtiger Lee

My question is when there are two LAN ports(eth0 & eth1) which connected to internet, I attempted to plug in and plug out eth0 and then eth1 status showed up “disconnect” and reconnected again.


From my past experience, this is not hardware issue. Due to there is the same situation on iMX28EVK board(Freescale dev Kit).

Our design team also tested mainline kernel from 2.6.35-3 to 3.5.0(Linux) which were provided by Freesacle. All of them have same issue.



We have done a lot of tests and found out when eth0 “plug in and plug out” that MAC and UDMA of eth0 will be reset by driver and eth1 will be influenced by eth0 which is not make sense. Therefore, we tried to use memory tools to write CPU register value directly and realized that when we wrote MAC0 HW_ENET_MAC_ECR reset bit or disabled HW_ENET_MAC_RCR RMII_MODE bit that will cause MAC of eth1 a reset situation and then reconnect to eth1.


Due to the conduct of iMX28 driver, our design team think it is related to iMX28 SoC.

Does anyone found this issue or have a solution


Best Regards,