Re: ohci & ads pyro card

[Andreas B. <and...@mu...>]

On Sat, Mar 18, 2000 at 04:08:28PM +1100, Sebastien Rougeaux wrote:
> >>>>> "Jeffrey" == Jeffrey B Mulligan <jb...@vi...> writes:
> Jeffrey> One thing I noticed is that the interrupt handler is getting called a
> Jeffrey> lot with event=0...  the IRQ is shared with other cards, does that
> Jeffrey> mean that handler will be called when one of the other sharing boards
> Jeffrey> generates an interrupt?
> 
> I am not completely sure about that.

It does mean that.  Every interrupt handler for a shared interrupt is
called when the interrupt occurs.

> If the interrupt handler is called
> with event=0, then nothing should happen and so no problem should be
> generated.

That's how it should be (it's a requirement for shared interrupts).

> But I thought that even if the interrupt is shared with 
> another device, the interrupt handler is only called when the corresponding
> device generate an interrupt... I should verify that in the doc.

Linux has no way of knowing which device caused the interrupt.  That
information is hidden in some chip register and only the driver knows
which register that is and how to interpret its contents.  Therefore
Linux has to call all handlers for a shared interrupt.

-- 
          Andreas E. Bombe <and...@mu...>
http://home.pages.de/~andreas.bombe/                DSA key 0x04880A44