I tested PMIC_ON_REQ state of i.MX7D with SABRE board.
I removed R350 that connected to PMIC_PWRON from Rest IC (TPS3808) output to see behavior of PMIC_ON_REQ out put when ONOFF input level.
PMIC_ON_REQ became always high when main power is up. You mentioned when tamper pin is low, PMIC_ON_REQ should be low according to i.MX7 Reset/Power-up from SVNS without button .
However, I set all tamper pins are low, but PMIC_ON_REQ became high when main power is up.
Does tamper pins are affected for PMIC_ON_REQ behavior?