Some, probably. But that firmware is self-contained to the converter chip, and doesn't have the ability to interact with your CPU's various subsystems. The i.M

Some, probably. But that firmware is self-contained to the converter chip, and doesn't have the ability to interact with your CPU's various subsystems. The i.MX8's HDMI core has independent access to the DDR memory, peripheral buses, timers, DMAs, and who knows what else. It's probably even running an RTOS of some kind, which might or might not include network drivers. Malicious firmware could compromise the security of your entire device. It's kind of the same problem that some folks have with Intel's IME. It could be fine and secure. Or maybe not, we just don't know. Nobody's saying that the i.MX8's HDMI firmware is malicious. It's probably fine. But we also don't know, because we can't inspect it. So if you were designing that chip into a security-critical setting, you'd have to wonder what might be running without your knowledge.