[PATCH v4 2/3] irqchip: GIC: Add support for irq_{get, set}_irqchip_state

[Feng Kan]

On Thu, May 14, 2015 at 3:32 AM, Linus Walleij <linus.walleij at linaro.org> wrote:
> On Wed, May 13, 2015 at 5:44 PM, Feng Kan <fkan at apm.com> wrote:
>
>> We are using the gpio driver with gpio_key for power button. The gpio
>> status can only be retrieved from the GIC register when the gpio is
>> acting as a interrupt.
>
> OK I understand so much. SPISR is a status register of the state
> of the IRQ lines of shared peripherals.
>
> But surely the GPIO block has its own status register, so are
> you saying that this register is unreliable?

When the GPIO is used as interrupt, the gpio block does not report the
status anymore. Which leaves us stuck with SPISR.
>
> I can think of a few reasons, like transient IRQs etc but
> what is actually causing this?

I won't say the obvious.
>
> Techically the GIC would normally be higher up the food
> chain, i.e. one IRQ on the GIC is cascaded to sub-IRQs on
> the GPIO chip by virtue of its own struct irq_chip and
> irqdomain. The exception is typically only systems where
> the GPIO block is fused with the IRQ controller so that each
> GPIO line has its own unique IRQ line on the primary,
> top-level interrupt controller.
>
> Which GPIO driver is this? Is it upstream?
Yes, it is upstream. It is the xgene slimpro gpio driver. I am starting to
think that we ought to switch to use some gpio poll driver rather than
using gpio-key.
>
> Yours,
> Linus Walleij