Why does callback irq_startup in struct irq_chip return _unsigned_ int ?

[Heiner Kallweit]

Hi Thomas,

just by chance I noticed that callback irq_startup in struct irq_chip
returns an unsigned int.
This doesn't seem to make sense as the result is a normal retval which
is casted to a signed int in function irq_startup() anyway.

Is there any specific reason for this or is it simply a bug?

Rgds, Heiner