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runtime PM

ranchu
Guru 20755 points

Hello,

In http://free-electrons.com/doc/omap-3530-pm.pdf under DPS page in is said as following

"Under Linux, matches the PM_RUNTIME option,  but not implemented for OMAP, instead, various  clocks and peripherals have an “auto­idle” mode."

What does it mean ? How DPS is enabled and what does it supports ?

Thanks you,

Ran

  • 0
    TI__Guru** 116100 points

    Hi Ran,

    Yes, the document seems to be right.

    The OMAP linux driver does not have runtime PM for some peripherals instead it support "auto-idle" or "auto sleep/wake"

    That means it would go to sleep mode when it is in idle and if found any access on the same peripheral it will come out from sleep automatically.

    All these implementations would take care by SoC ie pure internal hardware.

    Dynamic Power Switching (DPS) is the power management, it initiate low power mode dynamically for the peripherals when it is in idle condition.

  • 0 in reply to Titusrathinaraj Stalin
    Guru 20755 points

    Hi 

    I just not wanted to be sure about your terminology. What do you mean by "it will go to sleep mode when it is idle". Are both HW terms?. What is idle (condition of no clocks?) And what is sleep (power domain off?) Is it that the HW detects that there are no clocks? The omap config has runtime pm flag. Does it have any use for this purpose ?

    Thanks

    Ran

    Ran

  • 0 in reply to ranchu
    TI__Guru** 116100 points

    Hi Ran,

    I just not wanted to be sure about your terminology. What do you mean by "it will go to sleep mode when it is idle". Are both HW terms?.

    Yes. Hardware will take care but it is only for particular peripherals like SCR (switched central resource), ARM RAM etc.,

    What is idle (condition of no clocks?) And what is sleep (power domain off?)

    Is it that the HW detects that there are no clocks?

    Yes.

    The omap config has runtime pm flag. Does it have any use for this purpose ?

    Some of OMAP driver has runtime power management.

    Refer "omap_hsmmc_runtime_suspend"

    drivers/mmc/host/omap_hsmmc.c