A data transmission method, a chip, a controller, and a display device. The method is applied to a target driving chip in the display device. The display device includes a controller (01), a plurality of driving chips (02), and an in-cell touch display panel (03). The target driving chip is one of the plurality of driving chips (02). The target driving chip is respectively connected to the controller (01) and the in-cell touch display panel (03). The method includes: receiving state data acquired by the in-cell touch display panel, the state data being configured to reflect a working state of the in-cell touch display panel; and sending return data to the controller, the return data including the state data which includes control data.