why the system work at ondemand?

[ruiguifang]

Hi :

     our system start correctly, but the cpu clock only 392000hz,how can i change the cpu freq from ondemand to performance,when I echo performance > /sys/device/system/cpu/cpu0/cpufreq/scalling_setspeed  ,it turn out invalid  argument.any reply is ok

[nitinchaudhary]

Hi, below is the way to do it suppose the max CPU Frequency is 792 MHz and I want to change from ondemand to performance governor. You can add these lines to any of the init.rc scripts to make these settings

/*Setting the MAX Scaling frequency for CPU*/

echo "7920000" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq

echo "7920000" > /sys/devices/system/cpu/cpu1/cpufreq/scaling_max_freq

echo "7920000" > /sys/devices/system/cpu/cpu2/cpufreq/scaling_max_freq

echo "7920000" > /sys/devices/system/cpu/cpu3/cpufreq/scaling_max_freq

/*Setting the CPU Freq governor to Performance*/

echo "performance" > /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

echo "performance" > /sys/devices/system/cpu/cpu1/cpufreq/scaling_governor

echo "performance" > /sys/devices/system/cpu/cpu2/cpufreq/scaling_governor

echo "performance" > /sys/devices/system/cpu/cpu3/cpufreq/scaling_governor

/*Verifying the changes*/

cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_governor

cat /sys/devices/system/cpu/cpu*/cpufreq/scaling_max_freq

[ruiguifang · Accepted solution]

I find the answer now,  just type make menuconfig ,  setting the cpu option about freq

[igorpadykov]

using cpu freq driver it is necessary to take care of operating points

supported for specific processor, for example 3 for consumer grade

Table 6

http://cache.freescale.com/files/32bit/doc/data_sheet/IMX6DQCEC.pdf

and 2 for industrial grade

http://cache.freescale.com/files/32bit/doc/data_sheet/IMX6DQIEC.pdf

Best regards

igor