From patchwork Wed Mar 20 23:21:21 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jiri Kosina X-Patchwork-Id: 229509 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id AA8F62C00C4 for ; Thu, 21 Mar 2013 10:21:42 +1100 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754173Ab3CTXV0 (ORCPT ); Wed, 20 Mar 2013 19:21:26 -0400 Received: from cantor2.suse.de ([195.135.220.15]:33975 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753744Ab3CTXVZ (ORCPT ); Wed, 20 Mar 2013 19:21:25 -0400 Received: from relay1.suse.de (unknown [195.135.220.254]) by mx2.suse.de (Postfix) with ESMTP id B2B2FA4C0E; Thu, 21 Mar 2013 00:21:23 +0100 (CET) Date: Thu, 21 Mar 2013 00:21:21 +0100 (CET) From: Jiri Kosina To: Alan Stern , Greg KH Cc: Daniel Vetter , Chris Wilson , Harald Arnesen , Kernel development list , "Rafael J. Wysocki" , Peter Hurley , Thomas Meyer , Shawn Starr , USB list , linux-acpi@vger.kernel.org, Bjorn Helgaas , linux-pci@vger.kernel.org, Yinghai Lu , Imre Deak , Daniel Kurtz , dri-devel@lists.freedesktop.org, Thomas Gleixner , "H. Peter Anvin" , x86@kernel.org, Arkadiusz Miskiewicz 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)) In-Reply-To: Message-ID: References: User-Agent: Alpine 2.00 (LNX 1167 2008-08-23) MIME-Version: 1.0 Sender: linux-pci-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org 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 > > 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 > > Signed-off-by: Jiri Kosina > > 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 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 Signed-off-by: Jiri Kosina Acked-by: Daniel Vetter --- 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 +#include +#include + +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");