[LAD] Re: [LAU] Thinkpad R60 for Audio Update - Firewire Conflicts with Audio

[Paul Davis]

On Tue, 2007-04-10 at 14:34 +0200, Pieter Palmers wrote:

> I'm also wondering why/whether threaded IRQ's can't be software-demuxed 
> in the kernel. A very basic interrupt handler like this:
> 
> handle_irq() {
>    switch(irq_source) {
>      case HDA:
>        set_my_prio(high);
>        hda_handle_irq();
>      case 1394:
>        set_my_prio(low);
>        1394_handle_irq();
>    }
> }
> 
> Ingo's threaded IRQ stuff does something like this, but I don't quite 
> know the details of it. I'm under the impression that it allows setting 
> the priority of the 'handle_irq()' but not of the dispatched IRQ handlers.

yes, thats correct. the priority of the IRQ itself is based in h/w, and
is not affected by the scheduling class or priority of the kernel task
that runs the *_handle_irq(). the point of ingo's changes are that
*_handle_irq() runs in a dedicated task/thread per IRQ at a (relatively)
fixed priority.