RM9200 tuning

[Bernd Walter]

On Mon, Mar 08, 2010 at 12:46:38PM -0800, Stanislav Sedov wrote:
> On Mon, 8 Mar 2010 21:23:38 +0100
> Bernd Walter <ticso at cicely7.cicely.de> mentioned:
> 
> > Originally FreeBSD had assumed fixed clock rates.
> > Knowing the peripheral rate is important for e.g. UART bps dividers.
> > I think in the meantime it is possible to reconfigure the kernel to
> > different clock rates - if yes what are the kernel options for it?
> > Which would be the best place to reconfigure the PLL?
> > I know how to do it and that it is done by the loader right now, but
> > I would like to have it as a kernel tuneable.
> > All I need to know is a good place in the kernel startup.
> > 
> 
> I think the best place to do this would be the loader itself.  AFAIK, FreeBSD
> on AT91 doesn't assume any specific clock rate except the FSB clock rate and does
> the calibration of the CPU clock and xtal clock on startup.  One of solutions is to
> add a loader tunable that will allow you to pass the FSB clock rate from the loader,
> instead of assuming the constant value.

Well I still don't use a real loader, just the plain bootcode.
I would be very happy to switch to loader(8) with FICL, tuneables and
bootpromt.
Is it possible to do today?
I was with Warner using my elfbuild hardware for the first time when he
did the first steps on RM9200.
Therefor I'm probably still using obsolete old quick and dirty hacks.
If loader(8) can be used now it is the first thing I will change before
trying anything else.

-- 
B.Walter <bernd at bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.