x86, ioapic: Optimize pin_2_irq

Now that all ioapics have valid gsi_base values use this to
accellerate pin_2_irq.  In the case of acpi this also ensures
that pin_2_irq will compute the same irq value for an ioapic
pin as acpi will.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
LKML-Reference: <1269936436-7039-12-git-send-email-ebiederm@xmission.com>
Signed-off-by: H. Peter Anvin <hpa@zytor.com>

1 files changed, 4 insertions, 9 deletions

diff --git a/arch/x86/kernel/apic/io_apic.c b/arch/x86/kernel/apic/io_apic.c
index dae9240bd287..0d35f46929d1 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1019,7 +1019,7 @@ static inline int irq_trigger(int idx)
 int (*ioapic_renumber_irq)(int ioapic, int irq);
 static int pin_2_irq(int idx, int apic, int pin)
 {
-        int irq, i;
+        int irq;
         int bus = mp_irqs[idx].srcbus;
 
         /*
@@ -1031,18 +1031,13 @@ static int pin_2_irq(int idx, int apic, int pin)
         if (test_bit(bus, mp_bus_not_pci)) {
                 irq = mp_irqs[idx].srcbusirq;
         } else {
-                /*
-                 * PCI IRQs are mapped in order
-                 */
-                i = irq = 0;
-                while (i < apic)
-                        irq += nr_ioapic_registers[i++];
-                irq += pin;
+                u32 gsi = mp_gsi_routing[apic].gsi_base + pin;
                 /*
                  * For MPS mode, so far only needed by ES7000 platform
                  */
                 if (ioapic_renumber_irq)
-                        irq = ioapic_renumber_irq(apic, irq);
+                        gsi = ioapic_renumber_irq(apic, gsi);
+                irq = gsi;
         }
 
 #ifdef CONFIG_X86_32