modprobe fec causing smsc95xx reset & unregister

[billchen]

imx6q  4.1.15 kenel 

when I modprobe fec , caused smsc95xx 'USB disconnect' and unregistered then register , 

I want to know the reason. 

[billchen · Accepted solution]

I found the reason that problem actually was caused by hardware.  I need to change device tree of  'regulator' part ,

[billchen]

actually I want change eth0 to eth1 & eth0 to eth1, normally fec initialize at first， I compile fec && smsc95xx as module to change the sequence . it is ok in imx8 4.19,but in imx6q 4.1.15  when I modprobe fec, causing smsc95xx reset , I couldn't change the eth0 eth1 sequence 

[billchen]

thanks for your docment. I'll try KGDB .  I have tried ftrace tools .   It bothers me a lot ,because on our imx8mm board 4.19 kernel , it didn't happen ,   I can modprobe fec and won't influence the smsc95xx. 

[igorpadykov]

in general one can check if smsc95xx driver is built into the kernel ("=y") or built
as a module ("=m") or is not selected.

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm/configs/imx_v6_v7_defconfig?h=imx...

https://source.codeaurora.org/external/imx/linux-imx/tree/arch/arm/configs/imx_v6_v7_defconfig?h=imx...

Best regards
igor

[billchen]

On imx8 4.19  I have no trouble. 

[igorpadykov]

Hi Bill

one can try to rebuild all image from scratch, reset reason can be found using

debugging, one can use AN4553  Using Open Source Debugging Tools for Linux on i.MX Processors

Best regards
igor