This will be hard to explain.
We have an issue where the ADV7619 won't output stable vertical sync.
We have 3rd party processor output 1080p source. When a background content is high contrast. ADV7619 part output stable vertical sync. However, when we changed background to low contrast, ADV7619 part starts drop sync non-stop. We did some troubleshoots to narrow down. It seem a small percent of the ADV7619 part won't output stable vertical sync with combination of HDMI cable and output card. the same combination will work fine if it connected to the another ADV7619 part or other brand HDMI receiver. So it seem like ADV7619 is not optimal for some cable and source variables. When we play with some equalization setting in ADV7619, we able to make the bad ADV7619 to stable again by changing register 0x85 from 0x10 to 0x11 or 0x12. Since this is undocumented and outside from ADI recommended settings, We would like to check with ADI to make sure that we are okay to modify. In addition, we would like to understand what other way of setup equalization setting for this ADV7619 so that we can make it more robust.