There isn't any very clear definition of recommended power-up sequence in the data sheet for ADV7180, i.e. power supply -> PWRDWN pin -> RESET pin -> I2C activity, but I presume it may be similar to one discussed for ADV7188:
1) What would happen if the RESET signal was provided from the typical system POWER-ON reset - i.e. applied during power supply's rising time & still kept low well after power supply has stabilized - and the PWRDWN signal was also kept active low during that time until released later on by the host processor?
2) Could then the I2C operation be normaly used for programming the ADV7180?
3) Would it be required to first perform the Chip RESET - using Reset bit 0x0f - before programming the ADV7180?