I found a bug in the error handling in ACPI.

The issue here is the error handling within the ACPI layer.  gsi = 0 is a
valid return value from acpi_pci_irq_lookup, while gsi = (-1) is the value
returned when a PRT cannot be found.

This effects error handling within IRQ requests for IDE CD-ROM/DVD-ROM 
drives

Please apply this patch.

Thanks,

Prarit.

Signed-off-by: Prarit Bhargava <prarit-sJ/iWh9BUns@public.gmane.org>

===== drivers/acpi/pci_irq.c 1.35 vs edited =====
--- 1.35/drivers/acpi/pci_irq.c 2005-01-04 21:48:17 -05:00
+++ edited/drivers/acpi/pci_irq.c       2005-01-14 08:14:34 -05:00
@@ -487,10 +487,10 @@
         * If no PRT entry was found, we'll try to derive an IRQ from the
         * device's parent bridge.
         */
-       if (!gsi)
+       if (gsi == -1)
                gsi = acpi_pci_irq_derive(dev, pin,
                                          &edge_level, &active_high_low);
-       if (!gsi)
+       if (gsi == -1)
                return_VOID;

        /*