I have a GMSL1 link going to a MAX9276A. How can I check that the link is still operating correctly?
This is a common GMSL1 case where there is a microcontroller attached to a serializer and it's desireable to periodically check that the deserializer is still receiving correct data. Since I2C uses bits within the video data frames sent to the deserializer, checking I2C operation effectively checks link integrity. In some parts, such as the MAX9276A, there are user scratchpad registers called AVINFO and anything can be stored in them. A good idea is to send differing data to these registers and read it back; reading back correct data is a good indication that the link is working. In parts without these registers, simply reading back a register whose content is known and verifying its correctness is a good way to check link integrity. In either case, acknowledgement of the I2C command should also be checked for correctness.