Raspberry pi underclock, from 200 to 50MHz

Underclocking the raspberry pi, running a fresh archlinuxarm install, is funny.

At 50MHz text mode runs fine. But the usb chip seems to have issues (unresponsive keyboard). The provided firmware for the rpi isn't really an all purpose driver pack, IIUC they made decisions based on the original use-case for the SoC (video/dsp applications) like having naive hi-freq polling of the usb chip (again IIUC) which might overwhelm the throttled cpu.

At 100MHz almost no glitches, except on full terminal/screen redraw (htop, less, etc). Anything fancier will becoming a zen exercise.

I ran xorg + dwm + emacs (gtk) at 200MHz, it's harsh, but mostly because of graphic render; since I've used the lo-perf vesa driver I can't be too surprised, maybe with some X tweakings it can get smoother.

I'll try to run it around 20MHz, with ssh instead of usb keyboard. All this reminded me that my first computer was a Pentium 60 (fanless of course ;).

ps: clock settings are located in /boot/config.txt, a simple arm_freq=200 and a reboot will do. You can have min/max values to be used by cpufreq dynamic throttling. Follow here : http://www.raspberrypi.org/phpBB3/viewtopic.php?f=2&t=3042