I disabled the CPUFREQ stuff on PXA255 after that email, due to the =20
speed-change erratum on PXA255 which causes it to basically crash =20
some small percentage of the time when you change the CPU freq. On =20
verdex, you can re-enable this setting, though I'm not sure if the =20
driver is properly set up for PXA270. You should try asking possibly =20=
on the linux-arm kernel mailing list.
On Aug 15, 2007, at 7:36 AM, Sir Graham wrote:
> Then is there any way to set the speed of the intel Xsale CPU on =20
> the gumstix board?
> We need make some trys, for this need change the Gumstix 400Mhz to =20
> Craig, said me this link: http://article.gmane.org/=20
> CPUFREQ is now included in the standard gumstix kernel. This =20
> allows dynamic changing of the CPU frequency using the sysfs =20
> To change frequencies (simply), write the new CPU clock frequency to
> # echo 99533 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed
> The valid values for cpu frequency are: =20
> Note that strictly speaking, you're not supposed to clock a 200MHz =20
> CPU over 200MHz, nor a 400MHz CPU over 400MHz. It
> no doubt breaks some kind of warranty agreement.
> You can also read up on the cpufreq governors nd policies in the =20
> linux kernel source tree under Documentation/cpu-freq
> but it's not the best written of linux docs.
> Benchmarks for some of these frequencies are on the Wiki -- please =20
> feel free to add more datapoints if they're
> relevant; please don't add more numbers for the same frequencies =20
> where your results are just off ours
> by 0.01%. Also, we've got some basic power-draw numbers for the =20=
> various frequencies, but I don't think we've posted them yet on the =20=
> Basically though, slower =3D less power.
> The problem is that in the last versions of the flash DONT' EXISTS =20
> this directory "cpufreq" in the path
> ..and we can=C2=B4t create it.
> Anybody knows any way easy to put a Gumstix 400Mhz to 200Mhz clock =20
> Sir Graham.
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