Freescale's PF0100 PMIC should have VDDIO power tied to the same supply as the associated I2C supply on MX6.
There is a momentary on-chip sneak path on power-up if VDDIO is wired per the i.MX6 SABRE-AI automotive development platform. As a result, I2C power rail P3V3_DELAYED rises prematurely due to backfeed from P3V3 through the I2C port.
Note that on SABRE-AI, P3V3 powers up before P3V3_DELAYED.
Existing SABRE-AI design: PF0100 VDDIO is wired to P3V3.
Corrective action for mass production: Wire PF0100 VDDIO to P3V3_DELAYED; same supply as the associated I2C supplies on MX6 (NVCC_EIM0 and NVCC_GPIO).
Laboratory results attached.