Messages in this thread | | | Date | Wed, 20 Mar 2013 13:23:13 -0400 (EDT) | From | Alan Stern <> | Subject | 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, Jiri Kosina wrote:
> > I don't know of any way. In fact, I have been thinking of writing a > > test driver module, with a module parameter telling it which IRQ number > > to register for. It seems like the sort of thing that would be useful > > to have, from time to time. > > 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@suse.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@rowland.harvard.edu> > Signed-off-by: Jiri Kosina <jkosina@suse.cz>
This is just what I was thinking of. Three extremely minor suggestions...
> +static irqreturn_t dummy_interrupt(int irq, void *dev_id) > +{ > + static int count = 0; > + > + if (count == 0) { > + printk("dummy-irq: interrupt occured on IRQ %d\n", irq);
You probably should put a severity level here. KERN_INFO?
> + 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); > + return;
A return statement isn't needed here.
> +} > + > +module_init(dummy_irq_init); > +module_exit(dummy_irq_exit); > + > +MODULE_LICENSE("GPL"); > +MODULE_AUTHOR("Jiri Kosina"); > +module_param_named(irq, irq, uint, 0444);
module_param is good enough when the parameter's name is the same as the variable's name.
> +MODULE_PARM_DESC(irq, "The IRQ to register for");
Alan Stern
| |