Re: [PATCH 2/2] uio: add an of_genirq driver

Alan Cox
2009-06-14T23:11:18Z

> > + if (!uioinfo->irq)
> > + uioinfo->irq = UIO_IRQ_NONE;
>
> Please don't do this. It's inconsistent if all other UIO drivers require
> people to use UIO_IRQ_NONE and you also allow zero. UIO_IRQ_NONE was
> introduced because 0 may be a legal interrupt number on some platforms.

Zero is not a valid IRQ number in the kernel (except in arch specific
depths). IRQ numbers are also *unsigned* so -1 isn't a safe definition.

Zero means no IRQ. If any old UIO code is assuming otherwise it wants
fixing.

It is the job of the platform to map a physical IRQ 0 to some other
representation if it exists outside of arch specific code. This was
decided some years ago and a large part of the kernel simply doesn't
support any notion of a real IRQ 0.

Alan