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Register storing OPP value

Xi
Prodigy 210 points
Other Parts Discussed in Thread: TPS65950

Hi,

I'm trying to find the right register which stores the OPP value in DVFS feature. There are some OPP related registers in power management module but they look like controling status, not the 5 values.

Can any one please tell me which register should I write to, if there is any, when I want to set a value to OPP for changing CPU voltage and frequency?

Thanks!

  • 0
    Prodigy 210 points

    Can anyone answer this question?

    I have found a register which seems to control the voltage VDD1. It's in power module TPS65950. The name is VDD1_VSEL. It has 7 bit, so that looks like it covers more value of voltage instead of 5 level of OPP. I'm trying to find out if we can control through this register.

    I'm not sure if this is what I'm looking for. Please help me if anyone knows about it.

    Thanks!

  • 0 in reply to Xi
    TI__Prodigy 520 points

    Xi said:

    Can anyone answer this question?

    I have found a register which seems to control the voltage VDD1. It's in power module TPS65950. The name is VDD1_VSEL. It has 7 bit, so that looks like it covers more value of voltage instead of 5 level of OPP. I'm trying to find out if we can control through this register.

    yes, vsel reg contains the voltage, but modifying this beyond valid OMAP opp voltages might result in undefined behavior in the system.

  • 0 in reply to Nishanth Menon
    Genius 3685 points

    To put it in other words: If you know that you are doing, you can modify these registers how your like, but TI has only "validated" the given OPP values. The general strong recommendation is therefore to use one of these.

    It's however possible to run in something which would be i.e. OPP2.5 (in between OPP2 and OPP3 - or similar) in case you modify all the registers (affecting clocks and voltages) correctly and validate the setup on your own. Seen from a technical point of view this should be perfectly OK, although it might require a huge work for obtaining very little...

    Best regards
      Søren

  • 0 in reply to Nishanth Menon
    Prodigy 210 points

    Thanks Nishanth,

    It's fine to just control OPP, but I was wondering if there is some delay for voltage change modifying OPP inside the Linux system. Also, is there a kind of register who controls the OPP value (1 to 5) that I can directly write to it instead of writing the OPP configure file in the system? Thanks!