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Date:      Tue, 20 May 2014 15:03:24 +0000 (UTC)
From:      Hans Petter Selasky <hselasky@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r266470 - head/sys/arm/broadcom/bcm2835
Message-ID:  <201405201503.s4KF3ObK001443@svn.freebsd.org>
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Author: hselasky
Date: Tue May 20 15:03:23 2014
New Revision: 266470
URL: http://svnweb.freebsd.org/changeset/base/266470

Log:
  Optimise reading of pending interrupt registers. If there are no
  pending interrupt bits, skip the bit iteration loop.
  
  Reviewed by:	ian @

Modified:
  head/sys/arm/broadcom/bcm2835/bcm2835_intr.c

Modified: head/sys/arm/broadcom/bcm2835/bcm2835_intr.c
==============================================================================
--- head/sys/arm/broadcom/bcm2835/bcm2835_intr.c	Tue May 20 14:52:56 2014	(r266469)
+++ head/sys/arm/broadcom/bcm2835/bcm2835_intr.c	Tue May 20 15:03:23 2014	(r266470)
@@ -60,6 +60,7 @@ __FBSDID("$FreeBSD$");
 #define	BANK1_END	(BANK1_START + 32 - 1)
 #define	BANK2_START	(BANK1_START + 32)
 #define	BANK2_END	(BANK2_START + 32 - 1)
+#define	BANK3_START	(BANK2_START + 32)
 
 #define	IS_IRQ_BASIC(n)	(((n) >= 0) && ((n) < BANK1_START))
 #define	IS_IRQ_BANK1(n)	(((n) >= BANK1_START) && ((n) <= BANK1_END))
@@ -150,29 +151,36 @@ arm_get_next_irq(int last_irq)
 	/* Sanity check */
 	if (irq < 0)
 		irq = 0;
-	
+
 	/* TODO: should we mask last_irq? */
-	pending = intc_read_4(INTC_PENDING_BASIC);
-	while (irq < BANK1_START) {
-		if (pending & (1 << irq))
-			return irq;
-		irq++;
+	if (irq < BANK1_START) {
+		pending = intc_read_4(INTC_PENDING_BASIC);
+		if ((pending & 0xFF) == 0) {
+			irq  = BANK1_START;	/* skip to next bank */
+		} else do {
+			if (pending & (1 << irq))
+				return irq;
+			irq++;
+		} while (irq < BANK1_START);
 	}
-
-	pending = intc_read_4(INTC_PENDING_BANK1);
-	while (irq < BANK2_START) {
-		if (pending & (1 << IRQ_BANK1(irq)))
-			return irq;
-		irq++;
+	if (irq < BANK2_START) {
+		pending = intc_read_4(INTC_PENDING_BANK1);
+		if (pending == 0) {
+			irq  = BANK2_START;	/* skip to next bank */
+		} else do {
+			if (pending & (1 << IRQ_BANK1(irq)))
+				return irq;
+			irq++;
+		} while (irq < BANK2_START);
 	}
-
-	pending = intc_read_4(INTC_PENDING_BANK2);
-	while (irq <= BANK2_END) {
-		if (pending & (1 << IRQ_BANK2(irq)))
-			return irq;
-		irq++;
+	if (irq < BANK3_START) {
+		pending = intc_read_4(INTC_PENDING_BANK2);
+		if (pending != 0) do {
+			if (pending & (1 << IRQ_BANK2(irq)))
+				return irq;
+			irq++;
+		} while (irq < BANK3_START);
 	}
-
 	return (-1);
 }

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