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cpufreq cannot change freq/voltage

Alan Owan14
Prodigy 95 points
Other Parts Discussed in Thread: OMAP3530

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

  • 0
    TI__Expert 5960 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

  • 0 in reply to Jeff L
    Prodigy 95 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).