How can we change LDO bypassed to LDO enabled in iMAX6Q ?

[peteramond]

Hi All,

My custom hardware is based on i.MAX6Q processor and 800MHz Alliance memory.

According to following table how can I set LDO regulator to enable mode ? Which file has included following settings. I'm using nitrogen 6 max board related dtsi and uboot files. Can you tell me which dtsi or uboot file has included following terms ?

Regards,

Peter.

[Yuri]

Hello,

  Use description of kernel and device tree configurations in i.MX_Linux_Release_Notes

of Your NXP Linux BSP. For example, in the L4.9.88: “In standard DTB file, the LDO

bypass is enabled. Therefore, to use LDO device trees on configurations with CPU@1.2GHZ,

which does not support LDO bypass mode, it is important to enable LDO. The LDO is enabled

in the following DTB files:

• zImage-imx6q-sabresd-ldo.dtb

• zImage-imx6qp-sabresd-ldo.dtb

• zImage-imx6ul-9x9-evk-ldo.dtb

• zImage-imx6dl-sabresd-ldo.dtb

• zImage-imx6sl-evk-ldo.dtb

• zImage-imx6sx-sdb-ldo .dtb, zImage-imx6sx-sdb-reva-ldo.dtb”

Have a great day,

Yuri

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[peteramond]

Hi Yuri

Thank you for your quick response. If I'm using Nitrogen 6 Max dtb files. What should be the changes ? Nitrogen 6 Max dtbs are not included lod function in their dtbs.

Regards,

Peter.

[Yuri]

Hello,

 Use the attached file as an example (for imx6q sabresd ldo). 

Pay attention on regulator sections, also "anatop", "ldo" may be used 

as key words. 

Regards,

Yuri.

[peteramond]

Hi Yuri

Sorry to bother you again.

1) What are the default settings of the LDO regulator in kernel ? Is that LDO enable or LDO bypass ? Do you know any method to see the present status of the LDO in kernel ? Using devrgs command ?

When I read PMU_REG_CORE register using devrgs tools will it give the present settings ?

devregs 0x020C8140

2) Can we set this in uboot ?

3) And also some of my custom hardware designs are not working when it is 1.2V for VDDSOC_IN and GPU is highly stressed but when I give 1.375V to VDDSOC_IN, I can stress GPU more. Can you comment on this ? Can't I stress the GPU when I'm using LDO bypass mode ?

Regards,

Peter.

[Yuri]

Hello,

 i.MX6 internal PMU enables LDO by default, so the external input value must meet

LDO enable mode requirement during power up.

    After booting, SW can change to LDO bypass mode.

Regards,

Yuri.