lkml.org 
[lkml]   [2009]   [Jun]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH 2/2] uio: add an of_genirq driver
On Mon, Jun 15, 2009 at 12:12:07AM +0100, Alan Cox wrote:
> > > + 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.

The above uioinfo->irq is a signed long.

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

It doesn't. It won't complain about IRQ 0 and will pass it on to
request_irq, which will probably fail if it is as you say.

I did it that way because I saw IRQ 0 in /proc/interrupts on every PC...

>
> 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.

Funny.

> This was
> decided some years ago and a large part of the kernel simply doesn't
> support any notion of a real IRQ 0.

Can you tell me the reason for that decision or point me to some ml archive?

Thanks,
Hans

>
> Alan


\
 
 \ /
  Last update: 2009-06-15 01:49    [W:1.023 / U:0.292 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site