linux-kernel - [PATCH 12/15] x86 ioapic: Optimize pin_2

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Date:	Tue, 30 Mar 2010 01:07:13 -0700
From:	"Eric W. Biederman" <ebiederm@...ssion.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	linux-kernel@...r.kernel.org, Thomas Renninger <trenn@...e.de>,
	Suresh Siddha <suresh.b.siddha@...el.com>, len.brown@...el.com,
	Tony Luck <tony.luck@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>, linux-acpi@...r.kernel.org,
	Iranna D Ankad <iranna.ankad@...ibm.com>,
	Gary Hade <garyhade@...ibm.com>,
	Natalie Protasevich <protasnb@...il.com>,
	"Eric W. Biederman" <ebiederm@...ssion.com>
Subject: [PATCH 12/15] x86 ioapic: Optimize pin_2_irq

From: Eric W. Biederman <ebiederm@...ssion.com>

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@...ssion.com>
---
 arch/x86/kernel/apic/io_apic.c |   13 ++++---------
 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 c505fe0..764c74c 100644
--- a/arch/x86/kernel/apic/io_apic.c
+++ b/arch/x86/kernel/apic/io_apic.c
@@ -1018,7 +1018,7 @@ 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;
 
 	/*
@@ -1030,18 +1030,13 @@ 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
-- 
1.6.5.2.143.g8cc62

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