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targetroot@am335x-evm:~#
→Diva Frequency Scaling
The frequency of the CPU can be changed on the run using the Cpufreq framework (please refer to the documentation included into the linux-am33x/Documentation/cpu-freq directory of the kernel source tree). The cpufreq framework works in conjunction with the related driver & governor.
Cpufreq implementation controls the Linux OPP (Operating Performance Points) adjusting the Cortex-A8 core voltages and frequencies. CPUFreq is enabled by default in the Diva kernel configuration.
To view the supported OPP's (frequency in KHz)available governors:
<preclass="board-terminal">targetroot@am335x-evm:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequenciesscaling_available_governors275000 500000 600000 720000conservative ondemand powersave userspace performancetargetroot@am335x-evm:~#
</pre>
To view the supported OPP's (frequency in KHz),:
<preclass="board-terminal">targetroot@am335x-evm:~# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
275000 500000 600000 720000
</pre>
To change the OPP, :
<preclass="board-terminal">targetroot@am335x-evm:~# echo 275000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeedtargetroot@am335x-evm:~#
</pre>
Please note that OPP can be changed only using the '''userspace ''' governor. If governors like ondemand is used, OPP change happens automatically based on the system load.
For further details, please refer to the [http://processors.wiki.ti.com/index.php/AM335x_Linux_Power_Management_User_Guide AM335x Linux Power Management User Guide].
= Application notes =