Changing VDD_MAIN/VDD_MIPI_1P0 in iMX8

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Changing VDD_MAIN/VDD_MIPI_1P0 in iMX8

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Maddis
Contributor IV

Hi,

We have iMX8Q based HW running Linux. There is known issue that LVDS can be unstable on high temperature and fix for this is to raise VDD_MAIN/VDD_MIPI_1P0 from1.00V to 1.05V.

I checked manual and also U-boot/Linux sources, but I was not able to figure out how to actually do that change. So my question is that how do I change VDD_MAIN/VDD_MIPI_1P0 voltages? I did find some references for VDD_MAIN or VDD_MIPI_1P0 from device tree, can't remember now, but it was for iMX7.

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3 Replies

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igorpadykov
NXP Employee
NXP Employee

Hi mc

voltage control is described in sect.2.5 Power Management

i.MX Linux Reference Manual and can be changed with  SCFW Porting Kit

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Best regards
igor
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Maddis
Contributor IV

I did some digging and got somewhere, but then got stuck again.

I found this from SCFW - code:

--

/* Configure STBY voltage for SW1 (VDD_MAIN) */
if (board_parameter(BOARD_PARM_KS1_RETENTION)
== BOARD_PARM_KS1_RETENTION_ENABLE)
{
(void) PMIC_SET_VOLTAGE(PMIC_0_ADDR, PF8100_SW1, 800,
REG_STBY_MODE);
}

---

But I was not able to find where that PF8100_SW1 is being set to 1000mV. There were some ramp calculation from 800mv to 1000mv, but that value was not being used either. Is 1000mV default and I just should add my own call for 1050mV or how that supposed to work?

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Maddis
Contributor IV

Ah, I was afraid that it would be in SCFW. The only place I hadn't looked. Thanks I'll see if I can figure out how to do the change there. I've modified SCFW before so that's not the problem, just finding the correct place might be.

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