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Message-ID: <alpine.LNX.2.00.1303210018430.16237@pobox.suse.cz>
Date: Thu, 21 Mar 2013 00:21:21 +0100 (CET)
From: Jiri Kosina <jkosina@...e.cz>
To: Alan Stern <stern@...land.harvard.edu>, Greg KH <greg@...ah.com>
Cc: Daniel Vetter <daniel.vetter@...ll.ch>,
Chris Wilson <chris@...is-wilson.co.uk>,
Harald Arnesen <skogtun.linux@...il.com>,
Kernel development list <linux-kernel@...r.kernel.org>,
"Rafael J. Wysocki" <rjw@...k.pl>,
Peter Hurley <peter@...leysoftware.com>,
Thomas Meyer <thomas@...3r.de>,
Shawn Starr <shawn.starr@...ers.com>,
USB list <linux-usb@...r.kernel.org>,
linux-acpi@...r.kernel.org, Bjorn Helgaas <bhelgaas@...gle.com>,
linux-pci@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>,
Imre Deak <imre.deak@...el.com>,
Daniel Kurtz <djkurtz@...omium.org>,
dri-devel@...ts.freedesktop.org,
Thomas Gleixner <tglx@...utronix.de>,
"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
Arkadiusz Miskiewicz <a.miskiewicz@...il.com>
Subject: [PATCH] dummy-irq: introduce a dummy IRQ handler driver (was Re:
gm45 intel gfx can generate non-MSI irq# in MSI mode (was Re: [PATCH]
drm/i915: stop using GMBUS IRQs on Gen4 chips (was Re: [3.9-rc1] irq 16:
nobody cared (was [3.9-rc1] very poor interrupt respo))
On Wed, 20 Mar 2013, Alan Stern wrote:
> > Ok, so how about this?
> > Daniel, is it enough to make the problem appear on your system (by
> > building this into the kernel and booting with dummy-irq.irq=16)?
> >
> > Thanks.
> >
> > From: Jiri Kosina <jkosina@...e.cz>
> > Subject: [PATCH] dummy-irq: introduce a dummy IRQ handler driver
> >
> > This module accepts a single 'irq' parameter, which it should register for.
> >
> > Its sole purpose is to help with debugging of IRQ sharing problems, by
> > force-enabling IRQ that would otherwise be disabled.
> >
> > Suggested-by: Alan Stern <stern@...land.harvard.edu>
> > Signed-off-by: Jiri Kosina <jkosina@...e.cz>
>
> This is just what I was thinking of. Three extremely minor
> suggestions...
Thanks Alan. Updated version below.
Greg, willing to merge this simple debugging facility?
From: Jiri Kosina <jkosina@...e.cz>
Subject: [PATCH] dummy-irq: introduce a dummy IRQ handler driver
This module accepts a single 'irq' parameter, which it should register for.
Its sole purpose is to help with debugging of IRQ sharing problems, by
force-enabling IRQ that would otherwise be disabled.
Suggested-by: Alan Stern <stern@...land.harvard.edu>
Signed-off-by: Jiri Kosina <jkosina@...e.cz>
---
drivers/misc/Kconfig | 8 ++++++
drivers/misc/Makefile | 1 +
drivers/misc/dummy-irq.c | 59 ++++++++++++++++++++++++++++++++++++++++++++++
3 files changed, 68 insertions(+), 0 deletions(-)
create mode 100644 drivers/misc/dummy-irq.c
diff --git a/drivers/misc/Kconfig b/drivers/misc/Kconfig
index e83fdfe..69bb79d 100644
--- a/drivers/misc/Kconfig
+++ b/drivers/misc/Kconfig
@@ -93,6 +93,14 @@ config ATMEL_TCB_CLKSRC_BLOCK
TC can be used for other purposes, such as PWM generation and
interval timing.
+config DUMMY_IRQ
+ tristate "Dummy IRQ handler"
+ default n
+ ---help---
+ This module accepts a single 'irq' parameter, which it should register for.
+ The sole purpose of this module is to help with debugging of systems on
+ which spurious IRQs would happen on disabled IRQ vector.
+
config IBM_ASM
tristate "Device driver for IBM RSA service processor"
depends on X86 && PCI && INPUT
diff --git a/drivers/misc/Makefile b/drivers/misc/Makefile
index 35a1463..28ff261 100644
--- a/drivers/misc/Makefile
+++ b/drivers/misc/Makefile
@@ -13,6 +13,7 @@ obj-$(CONFIG_ATMEL_TCLIB) += atmel_tclib.o
obj-$(CONFIG_BMP085) += bmp085.o
obj-$(CONFIG_BMP085_I2C) += bmp085-i2c.o
obj-$(CONFIG_BMP085_SPI) += bmp085-spi.o
+obj-$(CONFIG_DUMMY_IRQ) += dummy-irq.o
obj-$(CONFIG_ICS932S401) += ics932s401.o
obj-$(CONFIG_LKDTM) += lkdtm.o
obj-$(CONFIG_TIFM_CORE) += tifm_core.o
diff --git a/drivers/misc/dummy-irq.c b/drivers/misc/dummy-irq.c
new file mode 100644
index 0000000..7014167
--- /dev/null
+++ b/drivers/misc/dummy-irq.c
@@ -0,0 +1,59 @@
+/*
+ * Dummy IRQ handler driver.
+ *
+ * This module only registers itself as a handler that is specified to it
+ * by the 'irq' parameter.
+ *
+ * The sole purpose of this module is to help with debugging of systems on
+ * which spurious IRQs would happen on disabled IRQ vector.
+ *
+ * Copyright (C) 2013 Jiri Kosina
+ */
+
+/*
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 as published by
+ * the Free Software Foundation.
+ */
+#include <linux/module.h>
+#include <linux/irq.h>
+#include <linux/interrupt.h>
+
+static int irq;
+
+static irqreturn_t dummy_interrupt(int irq, void *dev_id)
+{
+ static int count = 0;
+
+ if (count == 0) {
+ printk(KERN_INFO "dummy-irq: interrupt occured on IRQ %d\n",
+ irq);
+ count++;
+ }
+
+ return IRQ_NONE;
+}
+
+static int __init dummy_irq_init(void)
+{
+ if (request_irq(irq, &dummy_interrupt, IRQF_SHARED, "dummy_irq", &irq)) {
+ printk(KERN_ERR "dummy-irq: cannot register IRQ %d\n", irq);
+ return -EIO;
+ }
+ printk(KERN_INFO "dummy-irq: registered for IRQ %d\n", irq);
+ return 0;
+}
+
+static void __exit dummy_irq_exit(void)
+{
+ printk(KERN_INFO "dummy-irq unloaded\n");
+ free_irq(irq, &irq);
+}
+
+module_init(dummy_irq_init);
+module_exit(dummy_irq_exit);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Jiri Kosina");
+module_param(irq, uint, 0444);
+MODULE_PARM_DESC(irq, "The IRQ to register for");
--
Jiri Kosina
SUSE Labs
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