cpufreq stops working after a while

From: Mark Lord
Date: Fri Aug 11 2006 - 14:23:42 EST

One of my notebooks (Dell Latitude X1) has a 1.1GHz Pentium-M ULV processor.
This chip can change CPU speeds from 600 -> 800 -> 1100 Mhz.

I use speedstep-centrino with it, and after boot all is usually okay.
But after a few hours of operation, it stops shifting to the highest frequency
even under continuous 100% load (or not). Eventually it gets stuck at 600Mhz
and stays there until I reboot.

Sometimes rebooting doesn't even restore it.

/sys/devices/system/cpu/cpu0/cpufreq is all very normal looking,
showing the available frequencies and other info. All of the attribs
there look fine, except for "scaling_max_freq", which is what seems
to gradually get set smaller. For instance, right now it is set to 800000,
and it won't let me change it (echo 11000000 > scaling_max_freq has no effect.

WHY? And how can I fix it?

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