__irq_do_set

static void
__irq_do_set_handler(struct irq_desc *desc, irq_flow_handler_t handle,
             int is_chained, const char *name)
{
    if (!handle) {
        handle = handle_bad_irq;
    } else {
        struct irq_data *irq_data = &desc->irq_data;
#ifdef CONFIG_IRQ_DOMAIN_HIERARCHY
        /*
         * With hierarchical domains we might run into a
         * situation where the outermost chip is not yet set
         * up, but the inner chips are there.  Instead of
         * bailing we install the handler, but obviously we
         * cannot enable/startup the interrupt at this point.
         */
        while (irq_data) {
            if (irq_data->chip != &no_irq_chip)
                break;
            /*
             * Bail out if the outer chip is not set up
             * and the interrupt supposed to be started
             * right away.
             */
            if (WARN_ON(is_chained))
                return;
            /* Try the parent */
            irq_data = irq_data->parent_data;
        }
#endif
        if (WARN_ON(!irq_data || irq_data->chip == &no_irq_chip))
            return;
    }
 
    /* Uninstall? */
    if (handle == handle_bad_irq) {
        if (desc->irq_data.chip != &no_irq_chip)
            mask_ack_irq(desc);
        irq_state_set_disabled(desc);
        if (is_chained)
            desc->action = NULL;
        desc->depth = 1;
    }
    desc->handle_irq = handle;
    desc->name = name;
 
    if (handle != handle_bad_irq && is_chained) {
        unsigned int type = irqd_get_trigger_type(&desc->irq_data);
 
        /*
         * We're about to start this interrupt immediately,
         * hence the need to set the trigger configuration.
         * But the .set_type callback may have overridden the
         * flow handler, ignoring that we're dealing with a
         * chained interrupt. Reset it immediately because we
         * do know better.
         */
        if (type != IRQ_TYPE_NONE) {
            __irq_set_trigger(desc, type);
            desc->handle_irq = handle;
        }
 
        irq_settings_set_noprobe(desc);
        irq_settings_set_norequest(desc);
        irq_settings_set_nothread(desc);
        desc->action = &chained_action;
        irq_activate_and_startup(desc, IRQ_RESEND);
    }
}
函数源码
