LJCA_SPI_BUF_SIZE
(u8 *)r_packet, LJCA_SPI_BUF_SIZE);
(LJCA_SPI_BUF_SIZE - sizeof(struct ljca_spi_xfer_packet))
u8 obuf[LJCA_SPI_BUF_SIZE];
u8 ibuf[LJCA_SPI_BUF_SIZE];