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TPS65930 issue with VDD1. It's 1.46V but not 1.2V

Luffy Liu
Intellectual 300 points
Other Parts Discussed in Thread: TPS65930

We use tps65930 to power DM3730CUS100.

When the progress of xloader、uboot we test the VDD1 is 1.2V, which is normal.

But when the kernel is loaded, VDD1 turns to 1.46V immediately. the verson of the linux kernel is 2.6.32

We tried to adjust the regester to charge the output of VDD1, at the xloader、uboot it works. But when the kernel is loaded, it doesn't work.

What can we do to get the right output value?

  • 0
    TI__Expert 5450 points

    Luffy,

    When the kernel loads it takes control of the PMIC and can change settings to different value than those used for xloader or u-boot.  This may be done as part of DVFS or may be explicitly done in the kernel.  Please check your board file in the kernel to see if this rail is being adjusted to a different value.  If this rail is being used to power the processor and is controlled by DVFS then you may need to change your default governor to something like "userspace" so that the processor does not increase CPU speed and request a higher voltage.

    Sincerely,

    Chase

  • 0 in reply to Chase Maupin
    Intellectual 300 points
    Dear Chase,

    I can't find the code in the kernel, so I guess it is setting as part of DVFS. Is that OK if I disable the DVFS and set the value in the kernel? Will it have other negative effect if I do so?

    For I have tried to set the value in uboot and worked, can I ignored it in the kernel and just use the setting in the uboot?

    Many thanks!

    Luffy
  • 0 in reply to Luffy Liu
    TI__Expert 5450 points

    Luffy,

    You can try disabling DVFS in the kernel config and see what happens.  I would also recommend changing the governor to "userspace" to keep the kernel from increasing the CPU speed and needing additional voltage.

    Chase