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Usage of PMU unit from user space

lyf sci
Genius 3720 points

Hi Experts,

Is there any provision to use the PMU from user space for AM335x starter kit ?

Say capturing various events or configured to capture so..

  • 0
    TI__Expert 4475 points

    Hi,

    For better understanding a problem please read the 8.1 Power, Reset, and Clock Management from the TRM especially 8.1.4.2, 8.1.8 Power-Up/Down Sequence, 8.1.10 Voltage and Power Domains. Also very good sources are:
    http://processors.wiki.ti.com/index.php/Sitara_Linux_Training:_Power_Management
    http://processors.wiki.ti.com/index.php/Linux_Core_Power_Management_User%27s_Guide

    View also all available governors:
    root@am335x-evm# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_governors
        ondemand userspace performance conservative powersave
    View current governor:    
     root@am335x-evm # cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor         ondemand
    View and Change Frequency (OPP):
    First, set cpufreq governor to userspace
    View current frequency:
    root@am335x-evm# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq
    720000
    View current voltage:
    root@am335x-evm# cat /sys/class/regulator/regulator.3/microvolts
    1262500
    View Supported OPPs:
    root@am335x-evm# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
    275000 500000 600000 720000
    Change Frequency to 500MHz:
    root@am335x-evm# echo 500000 > /sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed

    BR
    Ivan

  • 0 in reply to Titusrathinaraj Stalin
    Genius 3720 points

    Hi Titus,

    Sorry I mean it for "Performance monitoring unit" inside ARM cortex A8 ?

    Is there any means to access the PMU registers inside AMR cortex A8 ?

  • 0 in reply to lyf sci
    TI__Guru** 116100 points

    http://processors.wiki.ti.com/index.php/Cortex-A8_Architecture#Cortex-A8_Performance_Monitor_Unit

    http://processors.wiki.ti.com/index.php/Oprofile_User%27s_Guide

    http://processors.wiki.ti.com/index.php/ARM_Multimedia_Users_Guide#oProfile

    http://www.slideshare.net/prabindh/cache-profiling-on-arm-linux

    http://lxr.free-electrons.com/source/arch/arm/mach-omap2/pmu.c