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Date:      Sun, 07 Jan 2001 09:25:14 -0700
From:      "Justin T. Gibbs" <gibbs@scsiguy.com>
To:        Warner Losh <imp@harmony.village.org>
Cc:        Peter Wemm <peter@netplex.com.au>, Jonathan Chen <jon@spock.org>, freebsd-mobile@FreeBSD.ORG
Subject:   Re: NEWCARD update 
Message-ID:  <200101071625.f07GPEs61330@aslan.scsiguy.com>
In-Reply-To: Your message of "Sun, 07 Jan 2001 09:19:12 MST." <200101071619.f07GJCs30019@harmony.village.org> 

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>In message <200101071432.f07EWrs59767@aslan.scsiguy.com> "Justin T. Gibbs" wri
>tes:
>: At least the 1251 on my Thinkpad has the ability to route legacy
>: interrupts directly.  Instead of the *extremely simple* interrupt
>: routing that I added in my recent patches, we need to determine if
>: the card in question is PCCARD or cardbus, and route the interrupt
>: accordingly.  Oh, and we need to do the correct setup for ISA style
>: DMA too which requires two of the eight ISA IRQ mux entries to
>: implement.
>
>One more thing to note.  On laptops, almost all cardbus bridges can
>directly set which interrupt to use as they are connected to the
>"south bridge" and can thus use the old ISA mode of operation.  On pci
>cards, you generally[*] don't have this connection, so you have to run
>in PCI only mode. Since PCI only mode will work on both
>configurations, we're trying to use it in preference to the direct
>mapping of interrupts.
>
>I don't know if that's what you are talking about being able to
>directly route the interrupts or not, but it is something to bear in
>mind.
>
>Warner
>
>[*] Compaq made a card that connected to the south bridge of an
>expansion box via a jumper...

Is there anyway to know if you have the connection?  The only reason
I think this might be interesting is to provide modem cards with
a unique IRQ so they can use fast interrupt handlers.

pccards going through a cardbus bridge should be able to share interrupts
so long as their drivers are smart enough to guard against "stray interrups".
This could be as simple as asking the bridge if the interrupt is for the card
manually or better yet, registering a proxy interrupt handler on behalf of the
child that only dispatches to the child if the interrupt bit for that slot is
set.

--
Justin



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