very strange cpufreq problem

[guillaume bort]

Hi all.

i've a very strange problem with cpufreq on my dell latitude d800 (intel
centrino). powernowd scale correctly my cpu when the AC adapter is
disconnected.

cat /proc/cpufreq :

          minimum CPU frequency  -  maximum CPU frequency  -  policy
CPU  0       600000 kHz ( 42 %)  -    1400000 kHz (100 %)  -  userspace

but when i connect my laptop to the AC adapter the maximum CPU frequency
down to 42%.

cat /proc/cpufreq :

          minimum CPU frequency  -  maximum CPU frequency  -  policy
CPU  0       600000 kHz ( 42 %)  -    600000 kHz ( 42 %)  -  userspace

and powernowd can't boost my cpu frequency.

very strange. any idea ?