Ya, the procedure that I'm using to set frequency worked on the older kernel.
to change the frequency of the tile, I write to the Global Clock Unit (GCU) Configuration Register (the address is 0x80) the wanted value, for example, to make the frequency 100 Mhz, I write "0x0380eff0" to the address 0x80.
If I soon read the curr_cpu_freq file, I'll find 100 . However, when I read this file after a few seconds, it will change automatically and return to the origin frequency of the core, for example 533.
I hope that I could clarify the problem.