Re: [PATCH v1] gpio: dwapb: mask/unmask IRQ when disable/enable it

[Thomas Gleixner <tglx@linutronix.de>]

On Sat, Dec 05 2020 at 22:58, Linus Walleij wrote:
> Sorry for top posting but I need the help of the irqchip maintainer
> Marc Z to hash this out.
>
> The mask/unmask/disable/enable semantics is something that
> you need to work with every day to understand right.

The patch is correct.

The irq_enable() callback is required to be a superset of
irq_unmask(). I.e. the core code expects it to do:

  1) Some preparatory work to enable the interrupt line

  2) Unmask the interrupt, which is why the masked state is cleared
     by the core after invoking the irq_enable() callback.

#2 is pretty obvious because if an interrupt chip does not implement the
irq_enable() callback the core defaults to irq_unmask()

Correspondingly the core expects from the irq_disable() callback:

   1) To mask the interrupt

   2) To do some extra work to disable the interrupt line

Same reasoning as above vs. #1 as the core fallback is to invoke the
irq_unmask() callback when the irq_disable() callback is not
implemented.

Thanks,

        tglx