how to setup PLL1 on 750FX

Benjamin Herrenschmidt benh at
Fri Jun 27 21:37:30 EST 2003

> I don't understand how it is that my machine didn't lockup when PLL1 was
> in the off state.

Well... I may have a bug making my low-speed-during-idle code not work
... Or maybe the PLL1 beeing off means the CPU will just continue
locking on PLL0...

> Anyway, I decided to set PLL1 in identify_cpu in misc.S.  Actually, I put
> the code to detect the 750fx and set PLL1 in a seperate method.  Here's
> what I have:

That looks fine overall but I didn't look at the assembly in details yet,
I'll try to take some time to review your code in more detail & eventually
commit to the linuxppc trees.

Another place where you want the real PVR is the CPU save/restore state
code in cpu_setup_6xx.S. That code is used for example to save the CPU
state before sleep and restore it on wakeup.


** Sent via the linuxppc-dev mail list. See

More information about the Linuxppc-dev mailing list