BOUNCE rtl@rtlinux.org: Approval required: (fwd)

[Der Herr Hofrat <der.herr@hofr.at>]

>From owner-rtl Sun Jun 24 19:48:16 2001
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Date: Wed, 20 Jun 2001 06:38:08 -0600
From: Victor Yodaiken <yodaiken@fsmlabs.com>
To: rtl@fsmlabs.com
Subject: Re: [rtl] off-topic: PCI interrupts
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 j.zhang@unsw.edu.au

The problem is caused by "level triggered interrupts" on shared lines.
In this situation, unless you clear the interrupt source (by e.g. reading a 
status register on the interrupting device), the interrupt remains asserted.
So you cannot unmask the interrupt controller. ISA is edge triggered.
Many boards have logic that handles this problem by mapping other 
interrupts to a controller so you can mask the individual source
instead of all PCI interrupts at that level

Device ----}
	   }slave controller ---> PCI interrupt level X ->
Device ----}

Or something like that.

On Mon, Jun 18, 2001 at 09:52:51PM -0400, Reef Morse wrote:
> In my application, I can check to see if my board triggered the interrupt.
> If it didn't, I just exit to other handlers.  It's about 4 lines of code in
> assembly, so it doesn't take much time.  This is on an ISA bus.  Does this
> apply for the PCI bus as well?
> 
> Regards, Reef Morse
> 
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