Hi, I have a confused problem as follows: I instantiate a i2c device with function i2c_register_board_info(); This function pre-declare the I2C devices which live on this bus and the call of it is before the real i2c bus driver loaded. In i2c_register_board_info(), __i2c_first_dynamic_bus_num = busnum +1; My i2c bus driver use i2c_add_adapter() to register adapter, In i2c_add_adapter(), res = idr_get_new_above(&i2c_adapter_idr, adapter, __i2c_first_dynamic_bus_num , &id); adapter->nr = id; That means if I pass busnum 0 to i2c_register_board_info(), but my i2c adapter will get busnum 1 and so it can't scan pre-declared i2c devices. In fact, I only have one i2c adapter. It seems I can't use i2c_add_adapter(), instead of using i2c_add_numbered_adapter, right? Best Regards, Lanttor -- To unsubscribe from this list: send the line "unsubscribe linux-i2c" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html