AMD Mobile processor does not throttle down

[Knappen]

I am running Ubuntu on a laptop with a AMD Mobile processor. The laptop runs
extreemly hot and drains the battery very quickly. It looks like the processor
does not throttle down. In the ACPI settings it says that throttling is not
supported for this processor but it actually is. It works fine under Windows and
other Linux distributions.

With a battery life around 30 minutes, Ubuntu really makes the laptop useless
unless plugged in.

[Matt Zimmerman (mdz)]

My understanding is that you don't want throttling; you want CPU frequency
scaling. Is CPU frequency scaling not working?

What kind of battery life do you see with other operating systems?

[Matthew Garrett (mjg59)]

The output from the lsmod command would be useful here, if possible

[Knappen (knappen)]

Yes, I do want CPU frequency scaling.

With Windows I get about 2 hours and the laptop hardly runs warm. With Ubuntu I
get about 30 minutes and the laptop runs really hot and the fan is at maximum.

[Matt Zimmerman (mdz)]

Please attach the output from "lsmod" and "dmesg" to the bug

[Knappen (knappen)]

Created an attachment (id=697)
dmesg

[Knappen (knappen)]

Created an attachment (id=698)
lsmod

[Knappen (knappen)]

I have attached output from lsmod and dmesg.

[Matthew Garrett (mjg59)]

Ok, it looks like this is simply down to the cpufreq hardware support module not
being loaded. If you edit /etc/modules and add

powernow-k7

on a line on its own and then reboot, does this help things?

[Knappen (knappen)]

Yes, that fixed the problem. The processor now scales down perfectly, the lowest
is 529 MHz. The fan stops and I am sure the battery life will increase
dramatically. Now the laptop runs like it should do.

Can I manually change the range? If I want it to go down to 400 MHz is it just
to change /proc/cpufreq ?

[Matt Zimmerman (mdz)]

This bug has been marked as a duplicate of bug 8200.