_pmbus_write_byte_data
ret = _pmbus_write_byte_data(client, page, reg, regval);
_pmbus_write_byte_data(client, -1,
_pmbus_write_byte_data(client, -1,
_pmbus_write_byte_data(client, -1,
_pmbus_write_byte_data(client, -1,
rv = _pmbus_write_byte_data(client, page,
rv = _pmbus_write_byte_data(client, page, reg, tmp);