BBB CPU clock (was: Re: FreeBSD on Cubieboard 2, UDOO and Galaxy Note 10.1 (Exynos).

[Bernd Walter]

On Tue, Oct 01, 2013 at 05:04:29AM +0800, Jia-Shiun Li wrote:
> On Mon, Sep 30, 2013 at 11:26 AM, Tim Kientzle <kientzle at freebsd.org> wrote:
> >
> > My understanding:
> >
> >   * We should query the PMIC to determine whether we're running from 5V supply or USB.
> >
> >    * Based on that, we should adjust the CPU clocks.  We should be able to run 1GHz from 5v supply.
> >
> > Connecting cpufreq would be a nice addition.
> 
> Hi Tim,
> 
> Yes you are right. I digged a bit the PMIC docs.
> I didn't realize that DCDC2/3 output to MPC/core are adjustable.
> 
> The PMIC capped USB input at 500mA by default, so if not changed otherwise,
> or to be safe with what most USB power supplies are, it is correct to only go up
> to 1GHz on DC input.
> 
> I played for a while manually setting PMIC from u-boot prompt, setting MPU volt
> to 1.325v, raise USB current limit, etc. but still cannot get it run
> above 800MHz.
> It always stopped booting at initing uhub. Looks like I need a bigger
> DC adapter.

I can do some tests with a lab supply.
But right now I'm doing some tests with another board.

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