A system may include a graphics controller and a display. The graphics controller may generate video data to display on the display. The display may include a display panel for displaying the video data, a backlight unit for providing the display panel with backlight, and a display timing controller for communicating with the graphics controller over a communications path. The communications path may include a video data path for conveying video data bits, an interrupt path for conveying interrupts, and a sideband control path for conveying control signals such as a backlight enable signal for the backlight unit. The graphics controller and timing controller may perform link training operations to assess link quality between the graphics controller and timing controller. The timing controller may use interrupts to inform the graphics controller of system status. Use of the interrupts may help the system minimize the time consumed during display power-up operations.