Subject: 82C59A troubles

From: Benjamin Herrenschmidt <[email-masked]>
Date: Wed, 21 Jul 1999 20:44:17 +0200

HI !

I'm porting the kernel and writing a bios for a custom design we are
doing, based on a SA110/285. I'm currently having some trouble with
handling of the 82C59A interrupt controller in the winbond. (The kernel
hangs as soon as it detects the chip, overflowed with interrupts from the
isa controller, it works fine but without IDE if i set isa_irq to -1).

Is the initialisation done in the kernel when isa_irq is not -1 somewhat
specific to a given hardware (Netwinder ?) like setting up level/edge
things ? Am I expected to initialize this beast from my bios ?

I'm just discovering this controller and... humm... no comment.

Is there any piece of well written explanation on how to setup this thing
? I've seen various docs but most of them suppose you already have some
knowledge about how the x86 interrupt mecanism works apparently.

Thanks for any tips...

-- 
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From: Philip Blundell <[email-masked]>
Date: Wed, 21 Jul 1999 20:55:59 +0100

>things ? Am I expected to initialize this beast from my bios ?

Not especially; the code in the kernel also works with CATS, and I gather with 
some other boards too.  ISA interrupts are almost always edge triggered.  I'm 
not aware of anything that your BIOS needs to set up.

The 8259 is a terrible chip.  If you prod it in the wrong way it will either 
go off sulking and refuse to generate any more interrupts, or start 
interrupting permanently.  But the existing ebsa-285 code should work I would 
have thought.

p.

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From: Benjamin Herrenschmidt <[email-masked]>
Date: Wed, 21 Jul 1999 23:39:06 +0200

>interrupting permanently.  But the existing ebsa-285 code should work I
would 

Hep, the problem is fixed, the HW engineer just forgot to invert the
interrupt output of the Winbond ... pfff.... The positive thing is that I
know how this damned chip work now after spending the day reading all
possible FAQs/docs/web pages on the subject ;-)