RE: request_irq not working.. what else should I do?

April 5, 2022


      I found request_irq(32+176, axpu_irq_handler, IRQF_SHARED, "axpu_irq",
&axpu_cdev); returned -22. (EINVALID).
And this is the sanity-check code of request_thread_irq function where
-EINVAL is returned.
Because I'm running my app/driver on ubuntu-20.04 (kernel 5.4.0-77) on a
virtual machine, I cannot debug the kernel code right now.
I suspect one of the "if (!desc)" case or "if
(!irq_settings_can_request(desc))" will be returning it -EINVAL.
Do I have to do something before I call request_irq? Can I use request_irq
in kernel module driver? (I think so).
 

/*
     * Sanity-check: shared interrupts must pass in a real dev-ID,
     * otherwise we'll have trouble later trying to figure out
     * which interrupt is which (messes up the interrupt freeing
     * logic etc).
     *
     * Also IRQF_COND_SUSPEND only makes sense for shared interrupts and
     * it cannot be set along with IRQF_NO_SUSPEND.
     */
    if (((irqflags & IRQF_SHARED) && !dev_id) ||
        (!(irqflags & IRQF_SHARED) && (irqflags & IRQF_COND_SUSPEND)) ||
        ((irqflags & IRQF_NO_SUSPEND) && (irqflags & IRQF_COND_SUSPEND)))
        return -EINVAL;

    desc = irq_to_desc(irq);
    if (!desc)
        return -EINVAL;
            
    if (!irq_settings_can_request(desc) ||
        WARN_ON(irq_settings_is_per_cpu_devid(desc)))
        return -EINVAL;
             
    if (!handler) {
        if (!thread_fn)
            return -EINVAL;
        handler = irq_default_primary_handler;
    }   

Thanks for reading.
Chan Kim
...
-----Original Message-----
From: Chan Kim <ckim@etri.re.kr>
Sent: Monday, April 4, 2022 11:16 PM
To: kernelnewbies@kernelnewbies.org
Subject: request_irq not working.. what else should I do?
Hello,
When I register interrupt handler in arm64 machine, I use request_irq( )
function defined below.
(on ubuntu 20.04 on qemu arm64 virtual machine)
static inline int __must_check
request_irq(unsigned int irq, irq_handler_t handler, unsigned long flags,
        const char *name, void *dev)
{
    return request_threaded_irq(irq, handler, NULL, flags, name, dev); }
I found even though I registered the handler for arm64 SPI (shared
peripheral interrupt) 176, it is not generating interrupt in the qemu
virtual machine. The OS should set the priority and enable it in the
interrupt controller but it doesn't work. That's what OS is for, isn't it?
But when I follow the qemu code, in the distributor stage, it says there
is no pending interrupt.
How can I set the interrupt priority using request_irq function above?
Thank you!
Chan Kim