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@xxxxxxx>
> 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@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
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
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