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To: Peter Wemm <peter@wemm.org>
Subject: Re: Problems with ata probing twice. 
Cc: Mike Smith <msmith@FreeBSD.ORG>,
	Makoto MATSUSHITA <matusita@jp.FreeBSD.org>, sos@freebsd.dk,
	current@FreeBSD.ORG
In-reply-to: Your message of "Sat, 07 Jul 2001 14:53:44 PDT."
		<20010707215344.4B1F2380F@overcee.netplex.com.au> 
References: <20010707215344.4B1F2380F@overcee.netplex.com.au>  
Date: Sat, 07 Jul 2001 16:22:38 -0600
From: Warner Losh <imp@harmony.village.org>
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In message <20010707215344.4B1F2380F@overcee.netplex.com.au> Peter Wemm writes:
: The upshot of this is that drivers should be setting RF_SHAREABLE if they
: themselves can handle the possibility that the motherboard is wired up for
: sharing their IRQ.  It is up to the bus controller to sort out what is
: really electrically shareable and what is not... the drivers themselves do
: not have this information (and should not be looking for it).  I expect
: the bus drivers need more work in this area.

OK.  Right now in current pcic_pci has code that looks like the
following:

struct resource *
pcic_alloc_resource(device_t dev, device_t child, int type, int *rid,
    u_long start, u_long end, u_long count, u_int flags)
{
	struct pcic_softc *sc = device_get_softc(dev);

	/*
	 * If we're routing via pci, we can share.
	 */
	if (sc->func_route == pci_parallel && type == SYS_RES_IRQ) {
		if (bootverbose)
			device_printf(child, "Forcing IRQ to %d\n", sc->irq);
		start = end = sc->irq;
		flags |= RF_SHAREABLE;
	}

	return (bus_generic_alloc_resource(dev, child, type, rid, start, end,
	    count, flags));
}

Which attempts to force the irq to be correct for the bridge.

The only potentially bogus thing in that is turning on the
RF_SHAREABLE flag.  Are you saying that all pccard drivers that don't
have a specific reason NOT to turn it on should turn it on and the
above code should look more like:

	if (type == SYS_RES_IRQ) {
		if (sc->func_route == pci_parallel)
			start = end = sc->irq;
		else
			flags &= ~RF_SHAREABLE;
	}

This would also mean that the isa bus would need code that look like:
	if (type == SYS_RES_IRQ)
		flags &= ~RF_SHAREABLE;
in it as well.

However, that's a problem because *some* ISA hardware can share
interrupts.  Timing Solutions makes hardware that does this :-)

Somehow, this doesn't seem quite right.

Warner

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