PEX0 and PEX2 issue in USB Lane Mapping cfg#5


Basic info:
Custom Carrier board
L4T R28.2.1
PEX0 lanes (x2) are connected to a onboard pcie switch.
PEX2 lane (x1) is connected to mini card connector.

Both the lanes PEX0 and PEX2 disappear when i connect a mPCIe card on the PEX2 lane but when nothing is connected on PEX2, PEX0 is working.

What could be the issue?


Please share the dmesg with us. Also, the tx2 adaptation guide and this link may help.

Hello WayneWWW

I have attached the dmesg txt file.

I have noticed the Plugin Manager has overwritten the device tree. So i checked the lanes using devmem2.
The results are okay for cfg#5
dmesg.txt (65.5 KB)


“The results are okay for cfg#5” -> Have you resolved the problem?

According to log, it looks the problem is still.


Let me clarify. I meant the output of devmem2 are correct. The lanes are owned by the respective controller as per cfg#5.

The problem still persists.

Could you make out what the reason is from the log?


According to your log, plugin-manager in dts still overwrites your dtb. So the config is still 4x1,1x1.

Please comment out that 3 fragments mentioned in below page.


Yes i just did that,The plugin manager is not over writting the DT anymore and PEX0 is back but PEX2 and PEX1 are not working.PEX1 had no issues previously.

I am suspecting USB Lane Mapping. How can i verify?

I have attached the DT file for reference.
DT.txt (4.59 KB)


If you configuration in dts is correct, the dmesg should show you have pcie 2,1,1.

Did the dmesg you shared already comment out plugin-manager fragment?


No the dmesg i shared earlier didn’t have the plugin-manager fragment commented. I did that now and updated in the last comment.

I can see pcie 2.1.1 configuration but PEX1 and PEX2 are non functional.

The dmesg attached now has the plugin-manager fragment commented.
dmesg.txt (71.9 KB)