IMX6: Ethernet PHY TX not working

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IMX6: Ethernet PHY TX not working

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vicpandit
Contributor II

We have a custom board that has IMX-6 connected to Micrel PHY (KSZ9031RNX).

This is a Magnatics less system that is 100BaseT.

Linux boots up fine, but the eth0 interface show activity only on RX side. all TX side is 0 bytes.

This leads to no dhcp address getting assigned to eth0.

# ifconfig eth0
eth0 Link encap:Ethernet HWaddr fa:fc:7e:7f:b5:92
inet6 addr: fe80::f8fc:7eff:fe7f:b592/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:220 errors:0 dropped:0 overruns:0 frame:0
TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:35227 (34.4 KiB) TX bytes:0 (0.0 B)

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I read some threads where it was mentioned that skew rate adjustments could solve such problem.

Following are our skew register settings. 

Could anyone point why TX side is not working? Any pointers would help us to make progress. We are stuck on this issue for around a month now.

# ./mmd 2 4
0x0000
# ./mmd 2 5
0x0000
# ./mmd 2 8
0xf3ff

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vicpandit
Contributor II

We finally found the issue.
Our design had not correctly connected the ENET_CRS_DV reset line from IMX-6q to the PHY.
Once we fixed this, both tx/rx is working fine at 100BaseT now.

Problem solved.