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Original question:

DM3730: how to power off the IVA, and wake up process ,where can I find the demo code.

Linux/DM3730: Command to idle, Wakeup DM3730 IVA in DVSDK?

Tony Tang
Mastermind 29172 points
Part Number: DM3730

Tool/software: Linux

Customer use DM3730 with: dvsdk_dm3730-evm_4_00_00_22_setuplinux

Want to Idle/Wakeup IVA to reduce power consumption dynamically, please suggest the command to do that in the DVSDK.

  • 0
    TI__Guru 65405 points
    Hi Tony,

    I'm not sure for dvsdk_dm3730-evm_4_00_00_22 but in the later DVSDKs as 4.02 and 4.03 the customer can use "omap3_iva_idle" function which forces the IVA2 into idle state so it can go into retention/off and thus allow full-chip retention/off.
    The customer can find definition in ./arch/arm/mach-omap2/pm34xx.c file.

    Regards,
    Tsvetolin Shulev
  • 0 in reply to Cvetolin Shulev-XID
    Prodigy 40 points

    Hi  Tsvetolin

    Thanks for your kindly reply, after the "omap3_iva_idle" command is executed,  IVA2 enter into sleep . At this point , would you please help confirm the below questions:

    1. When the IVA2 is wake up triggered by the interrupt ,should we need to reload the IVA2 code?

    2.After the IVA2 wake up , the IVA2 will go on  executing  at the PC point when the IVA2 was enter into sleep,right?

    3. If question 2 is right,  how can I deal with the L2 cache , the context in  L2 cache may be missed.

    4. How many milliseconds the IVA2 need to spend to executed the wake up process ?

    Regards

    Chenguang

  • 0 in reply to chenguang xue
    TI__Guru* 86900 points

    1. If you have the IVA2 memories in retention mode, then the code should remain in internal memory.   There is also an OFF mode which completely removes power from the IVA domain (for lower power), in which case the memory would not be retained.

    2. No, IVA2 sleep implies that the IVA2 power domain is turned off or in retention.  Thus, IVA2 will have to resume from reset vector.  The only way to continue to execute from the PC point after enabling sleep is to only fall into an inactive state, in other words, just turn of clocks to IVA while maintaining power

    3. You would have to reinitialize cache after IVA2 sleep if going to retention or off mode. 

    4. Sorry, i don't know this answer.  A lot of it depends on whether yo go into retention or off mode, interrupt latencies, etc.

    Regards,

    James  

  • 0 in reply to JJD
    Prodigy 40 points
    Hi James
    Thanks for your professional relay, I summarize the three modes which can save the OMAP power. Please point out my mistakes if any.
    1. Inactive mode , in this mode, the PC pointer can keep the lastest postion where the IVA2 was falling into inactive mode, then we still need to supply clock and voltage after the IVA2 is in inactive mode. we do not to reinitial the internal memory, the IVA2 can wake up quite quickly at the last PC pointer, How many power we can save in the incative mode?

    2. I am not very clear about the differences between the retetion mode and off mode, we do not need reload the code after the retetion mode,right. How many power we can save in the retetion mode and off mode?

    3. Can we find the detail demo code in the ./arch/arm/mach-omap2/pm34xx.c file ? We neeed to do some experiment to acquire the statistics about the power saving and wake up time which are very critical for us.

    Best Regards
    Chenguang