Subject: Re: MPC83xx ipic problem

From: André Schwarz <[email-masked]>
Date: Mon, 30 Jun 2008 19:14:19 +0200

Segher,

actually I'm the hardware designer ... :-) .... having trouble with 
software.

The outputs are open-drain and can be connected (wired-or) together.
Otherwise "shared irq" wouldn't be possible that easy.

cheers,
André

Segher Boessenkool wrote:
>> interrupt-map = <0x5800 0 0 1 &ipic 0x30 0x8      -> FPGA @ IRQ0
>>                  0x6000 0 0 1 &ipic 0x11 0x8      -> miniPCI INTA @ IRQ1
>>                  0x6000 0 0 2 &ipic 0x11 0x8>;    -> miniPCI INTB @ IRQ1
>>
>> Is it legal to use a single irq pin twice ?
>
> The device tree simply describes the hardware; if the hardware
> connects both INTXs to the same IPIC interrupt pin, then it is
> correct.  You'll have to ask a hardware designer whether it is
> okay to just tie the two lines together; I believe it is, for
> PCI, but you better ask someone who really knows :-)
>
>
> Segher
>

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