[GICv3 ITS]S2IDLE framework does not invoke syscore_ops in GICv3 ITS driver

[Youngmin Nam]

Hi.

On our SoC, we are using S2IDLE instead of S2R as a system suspend mode.
However, when I try to enable ARM GICv3 ITS driver (drivers/irqchip/irq-gic-v3-its.c),
I noticed that there is no proper way to invoke suspend/resume callback,
because it only uses syscore_ops, which is not called in an s2idle scenario.
Please refer to the codes below.

<drivers/irqchip/irq-gic-v3-its.c>
5028 static struct syscore_ops its_syscore_ops = {
5029         .suspend = its_save_disable,
5030         .resume = its_restore_enable,
5031 };
...
5803         register_syscore_ops(&its_syscore_ops);

<kernel/power/suspend.c>
444         if (state == PM_SUSPEND_TO_IDLE) {
445                 s2idle_loop();
446                 goto Platform_wake;
447         }
448
449         error = pm_sleep_disable_secondary_cpus();
450         if (error || suspend_test(TEST_CPUS)) {
451                 log_suspend_abort_reason("Disabling non-boot cpus failed");
452                 goto Enable_cpus;
453         }
454
455         arch_suspend_disable_irqs();
456         BUG_ON(!irqs_disabled());
457
458         system_state = SYSTEM_SUSPEND;
459
460         error = syscore_suspend();

How should we handle this situation ?