DLN2_I2C_BUF_SIZE
BUILD_BUG_ON(sizeof(*rx) > DLN2_I2C_BUF_SIZE);
dln2->buf = devm_kmalloc(dev, DLN2_I2C_BUF_SIZE, GFP_KERNEL);
BUILD_BUG_ON(sizeof(*tx) > DLN2_I2C_BUF_SIZE);