[BeagleBone Black Test PATCH 0/2] port latest u-boot

[Ian Lepore]

On Mon, 2014-04-07 at 18:41 -0700, Tim Kientzle wrote:
> On Apr 7, 2014, at 2:25 AM, Xuebing Wang <xbing6 at gmail.com> wrote:
> 
> > Hi Tim and all,
> > 
> > This is for discussion only. Would you please advice?
> > 
> > This is motivated by trying to increase CPU frequency for BeagleBone Black.
> > 
> > AM335x cpufreq is not supported yet. In order to achieve the goal to increase
> > CPU freq, I am thinking of a 2-step approach:
> > 1) port latest u-boot, which have cpufreq better organized
> > 2) tweak u-boot opp/freq later
> 
> Setting the processor frequency after the OS is running
> is not difficult.  The AM335x TRM shows exactly how to do it.
> 
> I would not change U-Boot but rather implement
> a FreeBSD driver that exposed a read/write sysctl
> to reprogram the CPU frequency.
> 
> Getting powerd to work with this should be straightforward.
> 
> Tim
> 

I agree with this, we should handle the frequency change in the kernel
rather than in u-boot.

On the other hand, I'm all for updating to a newer u-boot for other
reasons.  I did that for imx6, updating to 2014.01 in place of the
2013.04 that wandboard was using, and it went well.  In fact, pretty
much all I had to do was remove all the patches I had been using for
2013.04 except for turning on the API option and a couple other options.
There apparently have been recent fixes to some of the API stuff, such
as how storage devices are enumerated, which will help with the new
features added to ubldr that let you choose which device to load the
kernel from with u-boot env vars.

-- Ian