Display driver circuitry for electro-optic displays, in particular active matrix displays using organic light emitting diodes. The circuitry includes a driver to drive an electro-optic element in accordance with a drive voltage, a photosensitive device optically coupled to the electro-optic display element to pass a current dependent upon illumination reaching the photosensitive device, a first control device coupled between the photosensitive device and a data line and responsive to a first control signal on a first control line to couple the photosensitive device to the data line, and a second control device coupled between the photosensitive device and the driver and responsive to a second control signal on a second control line to couple the photosensitive device to the driver. The circuit can be operated in a number of different modes and provides flexible control of an electro-display element such as an organic LED pixel.