According to an example aspect of the present invention, there is provided an apparatus comprising a first processing core configured to generate first control signals and to control a display by providing the first control signals to the display via a first display interface, a second processing core configured to generate second control signals and to control the display by providing the second control signals to the display via a second display interface, and the first processing core being further configured to cause the second processing core to enter and leave a hibernation state based at least partly on a determination, by the first processing core, concerning an instruction from outside the apparatus.