Re: [RFC PATCH V2 3/8] genirq: Add runtime power management support for IRQ chips

[Ulf Hansson]

[...]

>> > I don't think using __free_irq() is the correct place to decrease the
>> > runtime PM usage count. It will keep the irqchip runtime resumed even
>> > if there are no irqs enabled for it.
>> >
>> > Instead I would rather allow the irqchip to be runtime suspended, when
>> > there are no irqs enabled on it.
>
> Which is a no no, as you might lose interrupts that way. We disable interrupts
> lazy, i.e. we do not mask them. So no, you cannot do that from
> enable/disable_irq().

Thanks for the input!

My main point around the approach suggested in $subject patch, is that
I don't think it's *enough* fine grained.

>From a runtime PM perspective, we should allow the irqchip to enter a
low power state when there are no IRQs enabled for it.

As enable|disable_irq() isn't the place to do runtime PM reference
counting from, perhaps there is another option? Maybe the irqchip
driver itself is better suited to take these decisions?

[...]

Kind regards
Uffe