From the forums and ADV7611 manuals, I understood that following are the possibilities for ADV7611 hot-plug implementation(i.e sending pulse on hot-plug detect pulse to source).
Case 1. At receiver side, connect +5v signal (pin 18) of HDMI connector to hot-plug detect signal (pin 19) of HDMI connector.
Case 2. Connect HPA_A(pin 1) signal of ADV7611 to hot-plug detect signal (pin 19) of HDMI connector. here we can send the pulse after some delay based on HPA_DELAY_SEL[3:0].
Case 3. Connect any GPIO line of the processor to hot-plug detect signal (pin 19) of HDMI connector.
In "case 1" hot-plug pulse will send automatically when HDMI cable is connected and in "case 2" also hot-plug signal will sent automatically (HPA_MANUAL = 0) after the delay set in HPA_DELAY_SEL[3:0] register.
Please correct me if the above understanding is not correct.
In "Case 3" hot plug pulse has to send manually from GPIO line to HPD. I have following doubts for this case, can you please help me on this.
1) Initially the hot-plug pulse should be low ? when we want the HDMI source to read EDID then we have to send high signal on GPIO?
2) How long we have to keep this pulse signal high on GPIO?
3) If we have both case 1 connection and case 3 connection on a board then will it have any side effects?