[PATCH RESEND] irqchip: omap-intc: improve IRQ handler

[PATCH RESEND] irqchip: omap-intc: improve IRQ handler

[Felipe Balbi]

as it turns out the current IRQ number will
*always* be available from SIR register which
renders the reads of PENDING registers as plain
unnecessary overhead.

In order to catch any situation where SIR reads
as zero, we're adding a WARN() to turn it into
a very verbose error and users actually report
it.

With this patch average running time of
omap_intc_handle_irq() reduced from about 28.5us
to 19.8us as measured by the kernel function
profiler.

Tested with BeagleBoneBlack Rev A5C.

Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
---
 drivers/irqchip/irq-omap-intc.c | 35 +++++------------------------------
 1 file changed, 5 insertions(+), 30 deletions(-)

diff --git a/drivers/irqchip/irq-omap-intc.c b/drivers/irqchip/irq-omap-intc.c
index a569c6dbd1d1..0706db624213 100644
--- a/drivers/irqchip/irq-omap-intc.c
+++ b/drivers/irqchip/irq-omap-intc.c
@@ -331,37 +331,12 @@ static int __init omap_init_irq(u32 base, struct device_node *node)
 static asmlinkage void __exception_irq_entry
 omap_intc_handle_irq(struct pt_regs *regs)
 {
-	u32 irqnr = 0;
-	int handled_irq = 0;
-	int i;
-
-	do {
-		for (i = 0; i < omap_nr_pending; i++) {
-			irqnr = intc_readl(INTC_PENDING_IRQ0 + (0x20 * i));
-			if (irqnr)
-				goto out;
-		}
-
-out:
-		if (!irqnr)
-			break;
-
-		irqnr = intc_readl(INTC_SIR);
-		irqnr &= ACTIVEIRQ_MASK;
+	u32 irqnr;
 
-		if (irqnr) {
-			handle_domain_irq(domain, irqnr, regs);
-			handled_irq = 1;
-		}
-	} while (irqnr);
-
-	/*
-	 * If an irq is masked or deasserted while active, we will
-	 * keep ending up here with no irq handled. So remove it from
-	 * the INTC with an ack.
-	 */
-	if (!handled_irq)
-		omap_ack_irq(NULL);
+	irqnr = intc_readl(INTC_SIR);
+	irqnr &= ACTIVEIRQ_MASK;
+	WARN(!irqnr, "Spurious IRQ ?\n");
+	handle_domain_irq(domain, irqnr, regs);
 }
 
 void __init omap3_init_irq(void)
-- 
2.4.4

Re: [PATCH RESEND] irqchip: omap-intc: improve IRQ handler

[Thomas Gleixner]

On Mon, 20 Jul 2015, Felipe Balbi wrote:
> +	irqnr = intc_readl(INTC_SIR);
> +	irqnr &= ACTIVEIRQ_MASK;
> +	WARN(!irqnr, "Spurious IRQ ?\n");

Shouldn't that be WARN_ONCE?

Thanks,

	tglx

Re: [PATCH RESEND] irqchip: omap-intc: improve IRQ handler

[Felipe Balbi]

[-- Attachment #1: Type: text/plain, Size: 2607 bytes --]

On Mon, Jul 20, 2015 at 10:44:08PM +0200, Thomas Gleixner wrote:
> On Mon, 20 Jul 2015, Felipe Balbi wrote:
> > +	irqnr = intc_readl(INTC_SIR);
> > +	irqnr &= ACTIVEIRQ_MASK;
> > +	WARN(!irqnr, "Spurious IRQ ?\n");
> 
> Shouldn't that be WARN_ONCE?

Sure, why not ?

8<--------------------------------------------------------------------

From a71590d725e54b888db278de6c278d2a106fc76d Mon Sep 17 00:00:00 2001
From: Felipe Balbi <balbi@ti.com>
Date: Fri, 2 Jan 2015 16:18:54 -0600
Subject: [PATCH RESEND v2] irqchip: omap-intc: improve IRQ handler

as it turns out the current IRQ number will
*always* be available from SIR register which
renders the reads of PENDING registers as plain
unnecessary overhead.

In order to catch any situation where SIR reads
as zero, we're adding a WARN() to turn it into
a very verbose error and users actually report
it.

With this patch average running time of
omap_intc_handle_irq() reduced from about 28.5us
to 19.8us as measured by the kernel function
profiler.

Tested with BeagleBoneBlack Rev A5C.

Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
---

Changes from V1:

 - replace WARN() with WARN_ONCE()

 drivers/irqchip/irq-omap-intc.c | 35 +++++------------------------------
 1 file changed, 5 insertions(+), 30 deletions(-)

diff --git a/drivers/irqchip/irq-omap-intc.c b/drivers/irqchip/irq-omap-intc.c
index a569c6dbd1d1..e15f10746310 100644
--- a/drivers/irqchip/irq-omap-intc.c
+++ b/drivers/irqchip/irq-omap-intc.c
@@ -331,37 +331,12 @@ static int __init omap_init_irq(u32 base, struct device_node *node)
 static asmlinkage void __exception_irq_entry
 omap_intc_handle_irq(struct pt_regs *regs)
 {
-	u32 irqnr = 0;
-	int handled_irq = 0;
-	int i;
-
-	do {
-		for (i = 0; i < omap_nr_pending; i++) {
-			irqnr = intc_readl(INTC_PENDING_IRQ0 + (0x20 * i));
-			if (irqnr)
-				goto out;
-		}
-
-out:
-		if (!irqnr)
-			break;
-
-		irqnr = intc_readl(INTC_SIR);
-		irqnr &= ACTIVEIRQ_MASK;
+	u32 irqnr;
 
-		if (irqnr) {
-			handle_domain_irq(domain, irqnr, regs);
-			handled_irq = 1;
-		}
-	} while (irqnr);
-
-	/*
-	 * If an irq is masked or deasserted while active, we will
-	 * keep ending up here with no irq handled. So remove it from
-	 * the INTC with an ack.
-	 */
-	if (!handled_irq)
-		omap_ack_irq(NULL);
+	irqnr = intc_readl(INTC_SIR);
+	irqnr &= ACTIVEIRQ_MASK;
+	WARN_ONCE(!irqnr, "Spurious IRQ ?\n");
+	handle_domain_irq(domain, irqnr, regs);
 }
 
 void __init omap3_init_irq(void)
-- 
2.4.4


-- 
balbi

[-- Attachment #2: Digital signature --]
[-- Type: application/pgp-signature, Size: 819 bytes --]

[tip:irq/core] irqchip: omap-intc: Improve IRQ handler

[tip-bot for Felipe Balbi]

Commit-ID:  6ed3464897cc825a75218653c710d673282dfcf8
Gitweb:     http://git.kernel.org/tip/6ed3464897cc825a75218653c710d673282dfcf8
Author:     Felipe Balbi <balbi@ti.com>
AuthorDate: Fri, 2 Jan 2015 16:18:54 -0600
Committer:  Thomas Gleixner <tglx@linutronix.de>
CommitDate: Wed, 22 Jul 2015 18:37:42 +0200

irqchip: omap-intc: Improve IRQ handler

As it turns out the current IRQ number will *always* be available from
SIR register which renders the reads of PENDING registers as plain
unnecessary overhead.

In order to catch any situation where SIR reads as zero, we're adding
a WARN() to turn it into a very verbose error and users actually
report it.

With this patch average running time of omap_intc_handle_irq() reduced
from about 28.5us to 19.8us as measured by the kernel function
profiler.

Tested with BeagleBoneBlack Rev A5C.

Tested-by: Tony Lindgren <tony@atomide.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Cc: Linux ARM Kernel Mailing List <linux-arm-kernel@lists.infradead.org>
Link: http://lkml.kernel.org/r/20150720204910.GH5394@saruman.tx.rr.com
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
 drivers/irqchip/irq-omap-intc.c | 35 +++++------------------------------
 1 file changed, 5 insertions(+), 30 deletions(-)

diff --git a/drivers/irqchip/irq-omap-intc.c b/drivers/irqchip/irq-omap-intc.c
index 6cc0ad5..8587d0f 100644
--- a/drivers/irqchip/irq-omap-intc.c
+++ b/drivers/irqchip/irq-omap-intc.c
@@ -330,37 +330,12 @@ static int __init omap_init_irq(u32 base, struct device_node *node)
 static asmlinkage void __exception_irq_entry
 omap_intc_handle_irq(struct pt_regs *regs)
 {
-	u32 irqnr = 0;
-	int handled_irq = 0;
-	int i;
-
-	do {
-		for (i = 0; i < omap_nr_pending; i++) {
-			irqnr = intc_readl(INTC_PENDING_IRQ0 + (0x20 * i));
-			if (irqnr)
-				goto out;
-		}
-
-out:
-		if (!irqnr)
-			break;
-
-		irqnr = intc_readl(INTC_SIR);
-		irqnr &= ACTIVEIRQ_MASK;
+	u32 irqnr;
 
-		if (irqnr) {
-			handle_domain_irq(domain, irqnr, regs);
-			handled_irq = 1;
-		}
-	} while (irqnr);
-
-	/*
-	 * If an irq is masked or deasserted while active, we will
-	 * keep ending up here with no irq handled. So remove it from
-	 * the INTC with an ack.
-	 */
-	if (!handled_irq)
-		omap_ack_irq(NULL);
+	irqnr = intc_readl(INTC_SIR);
+	irqnr &= ACTIVEIRQ_MASK;
+	WARN_ONCE(!irqnr, "Spurious IRQ ?\n");
+	handle_domain_irq(domain, irqnr, regs);
 }
 
 void __init omap3_init_irq(void)