Hi Chen, > Remove the 'acpiphp_callback' typedef as it is not used. [...] Good catch! This typedef was initially added in 2005, and then it stopped being used around the Kernel version 3.7 release, which is also when the sole user of this typedef called acpiphp_for_each_slot() has also been retired. Reviewed-by: Krzysztof Wilczyński <kw@xxxxxxxxx> Krzysztof