Clock / Timebase / Bus Frequencies Help

["richw@netcomuk.co.uk" <richw@netcomuk.co.uk>]

We've got an 8347 based board very similar to the A&M asp8347=2E Core cloc=
k
is 400MHz=2E Bus clock is 266666666Hz=2E
According to the data sheet for the 8347, the decrementer clock runs at a
quarter of the rate of the bus clock=2E I have two questions:
In arch/powerpc/boot/redboot-83xx=2Ec, the timebase clock is passed to
dt=5Ffixup=5Fcpu=5Fclocks() as bi=5Fbusfreq / 16=2E If I leave it like thi=
s, my
system clock runs approximately 4 times too fast=2E=20
Can anyone point me in the direction of an explanation for the div by 16
rather than 4=3F

If I change the call to dt=5Ffixup=5Fcpu=5Fclocks so that bi=5Fbusfreq/4 i=
s passed
in, then the clock runs more accurately=2E However, its still not correct=2E=

This gives a decrementer frequency of 66666666Hz, but if I hard code the
value to 66000000Hz, the clock runs accurately=2E
Can anyone shed any light on why the value passed in by the boot loader
(redboot) seems to be inaccurate=2E

Cheers,


Richard=2E



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