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Date:      Sat, 28 Sep 2013 01:18:07 +0200
From:      Bernd Walter <ticso@cicely7.cicely.de>
To:        Tim Kientzle <kientzle@freebsd.org>
Cc:        freebsd-arm@freebsd.org, ticso@cicely.de
Subject:   Re: FreeBSD on Cubieboard 2, UDOO and Galaxy Note 10.1 (Exynos).
Message-ID:  <20130927231807.GG82284@cicely7.cicely.de>
In-Reply-To: <8F8B0558-4B7A-4BC6-BF93-A89E5533C567@freebsd.org>
References:  <C085FFE7-994E-4371-B754-4846008E2048@yahoo.de> <CAGtf9xPDSy38_zDZssnfA8qqJjwUCQ_3yfoAm7DKYEzN3tdwUQ@mail.gmail.com> <1378866956.1111.608.camel@revolution.hippie.lan> <F7549C24-7B19-402A-914D-B70C9E483EA4@yahoo.de> <1379101800.1111.642.camel@revolution.hippie.lan> <20130926223120.GM65622@cicely7.cicely.de> <8F8B0558-4B7A-4BC6-BF93-A89E5533C567@freebsd.org>

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On Thu, Sep 26, 2013 at 07:43:39PM -0700, Tim Kientzle wrote:
> 
> On Sep 26, 2013, at 3:31 PM, Bernd Walter <ticso@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@bwct.de> http://www.bwct.de
Modbus/TCP Ethernet I/O Baugruppen, ARM basierte FreeBSD Rechner uvm.



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