Question please, could someone share the meaning of the parameters for drmModeSetPlane in libdrm?

int drmModeSetPlane(int fd, uint32_t plane_id, uint32_t crtc_id, uint32_t fb_id, uint32_t flags, int32_t crtc_x, int32_t crtc_y, uint32_t crtc_w, uint32_t crtc_h, uint32_t src_x, uint32_t src_y, uint32_t src_w, uint32_t src_h)

My problem is, whatever value I set, the video is not full screen mode, Anything I missed?

Thanks William