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TI Home » TI E2E Community » Support Forums » Digital Signal Processors (DSP) » OMAP™ Processors » OMAP35x Processors Forum » cpufreq cannot change freq/voltage
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    cpufreq cannot change freq/voltage

    This question is answered
    Alan Owan
    Posted by Alan Owan
    on Apr 01 2010 09:34 AM
    Prodigy40 points
    .config

    I cannot get cpufreq power management to work on the OMAP3530 EVM (Rev G). The frequency is always stuck at 500MHz and 1.2V. I've tried the PSP v2.01.03.11 and 3.0.0.4. (Based on OMAP-PM branch, according to software manifest).

    I configured the kernel starting from the default, and included changes for PM and PMIC chanpters in the PSP 3.0.0.4 user manual. I think I've uploaded the kernel .config. (I hope its attaced)

    See example command transcript below. I tried to change the governor settings, and tried directly writing frequecy values, but the frequency always is stuck at 500MHz, and I measure the VDD1 voltage always @1.2V. Anyone know what is wrong? (Config, commands, or problem with Kernel?)

    #cd /sys/devices/system/cpu/cpu0/cpufreq

    # cat scaling_governor
    userspace
    # cat cpuinfo_cur_freq
    500000
    # echo conservative > scaling_governor
    # cat cpuinfo_cur_freq
    500000
    # echo performance > scaling_governor
    # cat cpuinfo_cur_freq
    500000
    # cat stats/time_in_state
    720000 0
    600000 0
    550000 0
    500000 196271
    250000 0
    125000 0
    # echo 125000 > scaling_setspeed
    # cat cpuinfo_cur_freq
    500000

    omap 3530 EVM DVFS
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    • Jeff L
      Posted by Jeff L
      on Apr 01 2010 09:52 AM
      Verified Answer
      Verified by Travis Nguyen
      Expert4605 points

      Hi Alan,

      I'm using a PSP 3.0.0.4 kernel and below are the steps I took to be able to change the cpu frequency.

      I modified the kernel configuration using menuconfig as follows:

      I first enable CPU Frequency Scaling:

      CPU Power Management -> CPU Frequency scaling

      Enable: governor for userspace frequency scaling

      Set: Default CPUFreq governor (userspace)  ---> (userspace)

      Enable Smart reflex:

      System Type --> TI OMAP Implementations  ---> OMAP PM layer selection (PM layer implemented using SRF)  --> select SRF

      Once the kernel is booted you can modify the cpufreq below is an example and all the available frequencies.

      echo 500000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed

      cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
      720000 600000 550000 500000 250000 125000

      Jeff L

      If this post resolves your issue, please click on the verified answer.

      Regards,

      Jeff L

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    • Alan Owan
      Posted by Alan Owan
      on Apr 02 2010 14:55 PM
      Prodigy40 points

      Thanks for the help, the changes worked!

      I guess it was the : Set: Default CPUFreq governor (userspace)  ---> (userspace)

      that made the difference.  (I went back and tried again with the 'conservative' governor, and then I couldn't change speed again.

      (The SR tip was good too).

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