More properly handle links who only have 1 valid IRQ in their bitmask. The

old code special cased them too early which caused a few differences for
these sort of links relative to other PCI links:

- They were always re-routed via the BIOS call instead of assuming that
  they were already routed if the BIOS had programmed the IRQ into a
  matching device during POST.
- If the BIOS did route that link to a different IRQ that was marked as
  invalid, we trusted the $PIR table rather than the BIOS IRQ.

This change moves the special casing for "unique IRQ" links to only take
that into account when picking an IRQ for an unrouted link so that these
links will now not be routed if the BIOS appears to have routed it already
(some BIOSen have problems with that) and so that if the BIOS uses a
different IRQ than the $PIR, we trust the BIOS routing instead (this is
what we do for all other links as well).

Reported by:	Bruce Walter  walter of fortean com
MFC after:	1 week

1 files changed, 12 insertions, 13 deletions

diff --git a/sys/i386/pci/pci_pir.c b/sys/i386/pci/pci_pir.c
index 3dd10c1..52fb62f 100644
--- a/sys/i386/pci/pci_pir.c
+++ b/sys/i386/pci/pci_pir.c
@@ -398,12 +398,6 @@ pci_pir_parse(void)
 		pci_pir_dump_links();
 	}
 
-	/* Check for unique IRQ masks. */
-	TAILQ_FOREACH(pci_link, &pci_links, pl_links) {
-		if (pci_link->pl_irqmask != 0 && powerof2(pci_link->pl_irqmask))
-			pci_link->pl_irq = ffs(pci_link->pl_irqmask) - 1;
-	}
-
 	/*
 	 * Check to see if the BIOS has already routed any of the links by
 	 * checking each device connected to each link to see if it has a
@@ -516,15 +510,20 @@ pci_pir_route_interrupt(int bus, int device, int func, int pin)
 	}
 
 	/*
-	 * Pick a new interrupt if we don't have one already.  We look for
-	 * an interrupt from several different sets.  First, we check the
-	 * set of PCI only interrupts from the $PIR.  Second, we check the
-	 * set of known-good interrupts that the BIOS has already used.
-	 * Lastly, we check the "all possible valid IRQs" set.
+	 * Pick a new interrupt if we don't have one already.  We look
+	 * for an interrupt from several different sets.  First, if
+	 * this link only has one valid IRQ, use that.  Second, we
+	 * check the set of PCI only interrupts from the $PIR.  Third,
+	 * we check the set of known-good interrupts that the BIOS has
+	 * already used.  Lastly, we check the "all possible valid
+	 * IRQs" set.
 	 */
 	if (!PCI_INTERRUPT_VALID(pci_link->pl_irq)) {
-		irq = pci_pir_choose_irq(pci_link,
-		    pci_route_table->pt_header.ph_pci_irqs);
+		if (pci_link->pl_irqmask != 0 && powerof2(pci_link->pl_irqmask))
+			irq = ffs(pci_link->pl_irqmask) - 1;
+		else
+			irq = pci_pir_choose_irq(pci_link,
+			    pci_route_table->pt_header.ph_pci_irqs);
 		if (!PCI_INTERRUPT_VALID(irq))
 			irq = pci_pir_choose_irq(pci_link, pir_bios_irqs);
 		if (!PCI_INTERRUPT_VALID(irq))