cpu frequency scaling in Ubuntu?

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1

Hi all,

I just grabbed and compiled the latest stable kernel for Ubuntu Lucid (2.6.35.6-l5) and cpu frequency scaling doesn’t seem to work like it did with the Angstrom kernel. Do I need to configure something more in the menuconfig to get this to work or is it unsupported at the time? I am using a XM A2 board and I just compiled with the default config file in the sources.

Thanks

Kevin

2

Nope nothing really extra to configure, the Angstrom Kernel has few
more special bits including the omap3 cpufreq driver which isn't in
mainline yet..

http://git.kernel.org/?p=linux/kernel/git/khilman/linux-omap-pm.git;a=shortlog;h=refs/heads/pm-cpufreq

http://elinux.org/OMAP_Power_Management#What.27s_left_in_PM_branch

Regards,

3

When I apply that patch and try to build I get an error: plat/opp.h: No such file or directory

Am I missing other patches? Sorry for these questions I’ve never tried to patch kernels before, only make my own changes.

Thanks

Kevin

4

Sorry about that Kevin, i wasn't verbose enough..

Your going to need more then just the patches i linked to, to make this work..

It would be just better to run Kevin's PM branch or the Angstrom
2.6.32-psp kernel till more of this stuff gets merged upstream...

I think this is Kevin's head pm test tree:

http://git.kernel.org/?p=linux/kernel/git/khilman/linux-omap-pm.git;a=shortlog;h=refs/heads/pm

Regards,

5

Hello Robert,
I was looking for a method to scale the CPU frequency on my BBxM
running Ubuntu Maverick (https://wiki.ubuntu.com/ARM/
OMAPMaverickInstall)

Found this thread but the link given in the thread seems to be broken
and the method not working ( Kevin ?). I tried using cpufrequtils on
Ubuntu (as directed here http://www.thinkwiki.org/wiki/How_to_use_cpufrequtils)
but it wont load the BBxM processor drivers and hence doesn't works.

Can someone let me know a method using which I can run the BBxM at
1Ghz or atleast at a freq higher than the default one.

Thanks,
Mrityunjay

6

Hi Mrityunjay,

I'm getting closer to 1Ghz on the xM.. :wink:

Got frequency scaling to work this morning:
http://pastebin.com/wAe94bAt (300 -> 800Mhz steps)

Either from git head of my build script:
https://github.com/RobertCNelson/2.6.38-devel

or the v2.6.38-rc5-d3 that are being built/uploaded to rcn-ee.net/deb/
right now..

it's 2.6.38-rc5 + Nishanth Menon's sr1.5 tree:
http://gitorious.org/linux-omap-nm-sr/linux-omap-sr/commits/sr1.5

With this kernel, you can remove the "if xm limit to 800Mhz" setting i
had placed in the boot.scr, as mpurate=1000 doesn't hard lock the
kernel any more..

dmesg; [ 0.444610] Switched to new clocking rate
(Crystal/Core/MPU): 26.0/332/1000 MHz

I was kinda expecting the 300 -> 1,000 Mhz frequency options to show
up with the "cpufreq-info" probably missing one little detail....

Regards,