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how to enable /sys/power on dm368

Dmitryi konstantinovich
Prodigy 30 points

i use ti-dvsdk_dm368-evm_4_02_00_06? build linux kernel whit this flags

#
# Power management options
#
CONFIG_PM=y
CONFIG_PM_DEBUG=y
# CONFIG_PM_VERBOSE is not set
CONFIG_CAN_PM_TRACE=y
CONFIG_PM_SLEEP=y
CONFIG_SUSPEND=y
CONFIG_SUSPEND_FREEZER=y
CONFIG_APM_EMULATION=m
CONFIG_PM_RUNTIME=y
CONFIG_ARCH_SUSPEND_POSSIBLE=y
CONFIG_NET=y

but i hevent /sys/power

  • 0
    TI__Guru 65405 points

    Hi Dmitryi,

    All power management variables which are necessary are enabled. Also start 'make menuconfig' and enable the following settings if they are not enabled:

    Power management options

     -- Power Management support

     -- Power Management Debug Support

    and then rebuild the kernel.

    If still you haven't /sys/power could you check whether presents /sys folder and if it is true post the output of:

    ls /sys

    Also I found a similar issue related to missing nodes in the /sys folder tree. You can find the thread at:

    BR

    Tsvetolin Shulev

  • 0 in reply to Cvetolin Shulev-XID
    Guru 20755 points

    Hi Tsvetolin ,

    I hope you can have some idea for observed degredation in ethernet performance when power mode is enabled.

    I see that I get degregation when there if there is no activity in serial during the test (from time of starting the test till finishing the test). I thought That it means that cpu gets into retention in such scenario, but to my surprise the retention counter did not change during the test:

    ~ # cat /sys/devices/system/cpu/cpu0/cpuidle/state4/time

    70254200

    ~ # ./iperf -c 150.42.40.220 -w 2000

    WARNING: TCP window size set to 2000 bytes. A small window size

    will give poor performance. See the Iperf documentation.

    ------------------------------------------------------------

    Client connecting to 150.42.40.220, TCP port 5001

    TCP window size: 3.91 KByte (WARNING: requested 1.95 KByte)

    ------------------------------------------------------------

    [ 5] local 150.42.40.221 port 49380 connected with 150.42.40.220 port 5001

    [ ID] Interval Transfer Bandwidth

    [ 5] 0.0-10.0 sec 7.67 MBytes 6.43 Mbits/sec

    ~ # cat /sys/devices/system/cpu/cpu0/cpuidle/state4/time

    70254200

    What can be the reason for this degredation ?

    When I set in code sleep_while_idle = 0.I have no degredation .

    Is it that there is some failure in the counter progress that can explain this ? 

    Regards,

    Ran