VISFX_VRAM_WRITE_DEST
summitfb_write4(sc, VISFX_VRAM_WRITE_DEST, (y << 16) | x);
summitfb_write4(sc, VISFX_VRAM_WRITE_DEST,
summitfb_write4(sc, VISFX_VRAM_WRITE_DEST, ((y + i) << 16) | x);