alt Hacker NewsDo any monitors use the I2C multi-peripheral feature to allow both DDC communication and an I2C EEPROM to exist at different addresses on the same bus? Or is it cheaper to integrate functionality into a controller chip? (Though DP tunnels EDID over the aux bus, and (I assume) doesn't use an EEPROM to begin with.)
The specification is explicitly designed to allow for it, but I honestly doubt it is very popular - if used at all.
There are two main issues here. The first is that the standard EDID EEPROM is very limited in size, and a lot of monitors need more space. VESA solved this by adding a dummy "segment selector" register, located on a separate I2C address. This makes it incompatible with off-the-shelf I2C EEPROM chips, so you'd need some kind of custom EDID-specific EEPROM chip anyways.
The second issue is that most monitors have multiple input ports. A regular EEPROM chip can only be hooked up to a single port (I2C itself supports it, but the spec forbids it), so you'd need one EEPROM chip per port. That gets expensive quite quickly.
If you're already implementing DDC/CI via some kind of microcontroller, why not have it deal with EDID as well? Heck, you could even give the microcontroller a separate connection to an EEPROM to make it easier to program! The EDID part is absolutely trivial, I bet you could implement it in two dozen instructions without even trying very hard. No reason to make it even harder for yourself by keeping it separate.