As I understand the process, correctly deinterlacing native 1080i/60 content requires motion adaptive deinterlacing.
If there is no motion in the image, then two consecutive odd & even interlaced fields are perfectly correlated and can be combined into one progressive frame, which is displayed twice to maintain the 60 Hz frame rate.
If there is motion in the image, then two consecutive odd & even interlaced fields are not perfectly correlated and cannot be combined into one progressive frame. Instead, line doubling or line interpolation synthesizes the missing lines in each field, thereby artificially converting each interlaced field into a progressive frame.
Motion adaptive deinterlacing may shift between the two methods after each pair of fields. Or it may utilize the two methods simultaneously w/in each pair of fields, applying the first method to any static segments of the image, the second method to any motive segments of the image.