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Make OMAP4460 go deepest possible sleep mode

Girija
Prodigy 30 points

Hi,

I am trying to suspend/sleep OMAP4460 and put the to system consume lowest possible power.


To make the system suspend                         

  "echo mem > /sys/power/state"
  • With this the system suspends, but there is no considerable reduction in the  power consumed by the system.
  •  Refer me, what are the modules that go down upon suspend.
  • What will be the time taken for OMAP to suspend and resume.

In data manual it is mentioned that we can achieve another mode called power off mode.
  • What is the procedure to achieve that mode of operation.
  • Could the system be resumed back to its original condition from where power off is called, Which modules will be active in that mode.

Power consumption also relies on clocking events to the modules.
  • It is specified in the data sheet, it is hardware driven.
  • From software perspective, does anything to be done such that the power consumption reduces.

Please bring to my notice, whatever the possibilities available to meet power efficiency of OMAP4460. My ultimate aim is to reduce the power consumption of OMAP and its perpherals to lowest possible level when the system is idle.
Thanks,
Girija
  • 0
    TI__Genius 10965 points

    Hi Girija,

    I think you are not properly suspending your device.

    What kernel  release are you using?

    Take a look at this article in order to understand how suspend is done.

    http://www.omappedia.org/wiki/Power_Management_Debug_and_Profiling

    Regards,

    Boyko

  • 0 in reply to Boyko Kazakov
    Prodigy 30 points
    Hi Boyko,
    Thanks for your reply.

    We could able to put the system in suspend mode. Earlier, since the CPU was not running CPU intensive task and it was consuming already less power (due to CPU governance) and we could see much difference in the power consumption.
     
    Once CPU utilization was increased, we could see good amount of power reduction (around 60%)​.
    In the OMAP data sheet, it is mentioned two power modes (Suspend mode & Deep Sleep mode).
    Is there a way to put OMAP4460 in deep sleep mode ?
    Is there any difference between suspend and deep sleep mode ?
    If yes, then how to put it into deep sleep mode. when suspend, whether DDR will be in self-refresh mode ?
    Thanks,
    Girija
  • 0 in reply to Girija
    TI__Genius 10965 points
    Hi Girija,

    By default, retention is the deepest sleep state attempted. To enable power domain transitions to off mode

    # echo 1 > /debug/pm_debug/enable_off_mode

    Regards,
    Boyko
  • 0 in reply to Boyko Kazakov
    Prodigy 30 points
    Hi,

    Thanks for the information,

    I need some more clarifcations regarding this omap power off mode.

    The kernel release we use is 3.0.31, the ES revision of the omap4460 we use is ES1.1

    It is mentioned in this site: http://processors.wiki.ti.com/index.php/TI-Android-GingerBread-2.3.4-DevKit-2.1_PortingGuides#Power_Management - Core domain cannot enter into OFF mode if the board ES revision is less than 1.2

    Please suggest, whether power off mode is possible or not possible. Is there any work around to make the system support power off mode.

    Thanks,
    Girija.