second ethernet port do not work arfter suddenly power down

[cyndent]

i have both 6ul/6ull board and they all have two etherent port using lan8720a phy.

linux kernel i have tried 4.15/4.4.

After warm reboot, the second ethernet port works well.

But after cold reboot，the second ethernet port do not work

i have known that it's a power-on sequence problem.But i'm a beginner of linux,i do not know what to do next.

Can someone tell me how to check about it?

Thanks!

[Bio_TICFSL]

Hi Mingyang,

The table Reset Priorities, Sources, Types, and Behavior from user's manual used by ALU. It shows the reset propagation to IP bloc. There is 3 warm reset depending of sources ( see below ). I guess that the one connected to ENET is system_rst_b because it drives functional modules. Based on table below, it means that ENET isn't reseted. The is also an other useful drawing on Reset Diagram.

Regards

[cyndent]

Hi Bio_TICFSL:

   Sorry for the late reply. I have check the document and find the difference as you say above.

   But i'm still confusing about the process that when does it work and how can i fix it? Is it working in kernel or uboot? or just in chips that i can not modify it? or i have make some modifies in hardware? 

   i have searched in kernel and uboot but i have find nothing about system_rst_b.

   Can you give some advices about that？ Thanks very much.