Changing VDD_MAIN/VDD_MIPI_1P0 in iMX8

[Maddis]

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.

[igorpadykov]

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

Best regards
igor
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[Maddis]

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?

[Maddis]

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.