When I connect a 4kp60 HDMI source, it works well at first but the video drops after 15 to 45 minutes.
HDMI RX reports bad link quality:
This is a known issue in HDMI v3.1 in Vivado 2018.1 and 2018.2. It has been fixed in the 2018.3 release and later versions
When the issue occurs, the link error counter increases, the user might see display blinks, and then the RX stream is recovered quickly.
To detect this issue, you can use the API XV_HdmiRxSs_ReportLinkQuality to print out the link quality.
This issue only occurs in the HDMI 2.0 resolution where the scrambler needs to be enabled, for example with 4kP60 RGB.