How i change the frequency of I2C1 ?

Hallo,

i want to change the frequency of I2C1 but it doesnt work. i have read some tutorials but everbody says a different way and now i am really confused.

  1. In which directory i have to change the frequency? some says that you can change in the /boot/dtbs/3.83…/ - directory and others say that you have to change in the /lib/firmware…I dont understand now what i have to do?

Can me anybody help?