[U-Boot-Users] U-Boot wrong cpu frequency calculation when setting PLPRCR directly

Antonio Di Bacco dibacco at libero.it
Sat Jan 20 09:45:00 CET 2007

Hi all,

I setup the cpu frequency of a Freescale MPC880 directly providing a value
for the PLPRCR register. When the u-boot (1.2.0 and previous) starts, in
file speed.c it makes a calculation to display the CPU frequency based on
fields in PLPRCR. Working with integers it makes an approximation that
leads to a wrong cpu frequency in my case 130 Mhz instead of 132 Mhz). As a
consequence my clock was wrong gaining 20 minutes per day. It is easy to
patch the problem. If someone is interested I'll give him the patch.


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