[U-Boot] /proc/cpuinfo Revision field is 0000 on raspberry pi after booting with u-boot

[Christian Erhardt]

Hello,

i'm upcycling an old stereo amplifier and using an raspberry pi to do 
this. Since i didn't want to unscrew the cover everytime i want to do an 
update, i thought booting with u-boot from a secondary partition would 
be a good idea. I'm using buildroot to create a customized kernel / 
system (default raspberry 3.12.y with minor adjustments for my wifi card).

The kernel boots fine and the system is working. The issue is, that when 
i do a 'cat /proc/cpuinfo' the Revision field is set to 0000. When i 
boot the kernel directly, without u-boot, it reports 000e.

The problem is, that the python gpio library is checking this revision 
field to determine the right configuration. So the gpio stuff is not 
working an complaining that my board is not a raspberry pi.

It seems to me, that this issue is related to u-boot, but i have no clue 
why this is happening and what i can do about it.

If i can provide any more information, let me know.

Regards

Christian