US Patent 7899941 Displayport I

Circuits, methods, and apparatus that allow a DisplayPort compatible host device to control data transactions over an I2C bus when communicating with a legacy monitor. One example includes an adapter having a compatibility register that may have a number of locations, where at least some of the locations correspond to I2C bus speeds. Values stored at these locations can indicate whether the adapter is compatible or incompatible with the corresponding I2C bus speed. Another example includes an adapter having a speed register that may have a number of locations, where at least some of the locations correspond to I2C bus speeds. A defined value written to one of these locations dictates the corresponding I2C bus speed.