I2C_PACKET_HEADER_SIZE
xfer_size = i2c_dev->msg_len + I2C_PACKET_HEADER_SIZE;
memcpy(i2c_dev->dma_buf + I2C_PACKET_HEADER_SIZE,
.max_write_len = SZ_4K - I2C_PACKET_HEADER_SIZE,
.max_write_len = SZ_64K - I2C_PACKET_HEADER_SIZE,
I2C_PACKET_HEADER_SIZE;