FreeBSD on Cubieboard 2, UDOO and Galaxy Note 10.1 (Exynos).

[Bernd Walter]

On Thu, Sep 26, 2013 at 07:43:39PM -0700, Tim Kientzle wrote:
> 
> On Sep 26, 2013, at 3:31 PM, Bernd Walter <ticso at cicely7.cicely.de> wrote:
> 
> > I also noted that the Beaglebone Black seems to run at 550MHz only.
> > I've found out from NetBSD mailinglist, that the PLL must be
> > reprogrammed for higer frequency and the core voltage needs adjustment
> > too.
> > Of those 3 boards the BBB was the only board mention CPU frequency at all.
> 
> I've not looked into the code required, but I know some of the issues:
> 
> * For the older "white" Beaglebone, at least, the CPU frequency
>    needs to be set properly depending on the power supply.  So
>    "someone" needs to read the PMIC and determine whether
>    power is coming from the 5V input or from USB.  In the latter
>    case, I believe the lower frequency may be appropriate.
> 
> * For BB White, I believe the "someone" was U-Boot; the FreeBSD
>   kernel just assumed the CPU was already properly initialized.
>   I haven't looked to see if the U-Boot we're using now does power
>   config for BBB.
> 
> * We should add a PMIC driver and do this setting in our kernel.

This matches with what I got from reading some mails on a NetBSD list:
http://mail-index.netbsd.org/port-arm/2013/08/01/msg001932.html

I didn't find any definitive answer about barrel plug vs. USB supply.
It seems that via USB the performance is to be reduced.
However using a lab supply I measured via barrel plug supply 270mA with
550MHz FreBSD and 320mA with preinstalled Linux at unknown frequency.
Maybe precaution for higher load, or USB devices sucking power.

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