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

From: Feng Kan
Date: Thu May 14 2015 - 16:15:08 EST

On Thu, May 14, 2015 at 3:32 AM, Linus Walleij <linus.walleij@xxxxxxxxxx> wrote:
> On Wed, May 13, 2015 at 5:44 PM, Feng Kan <fkan@xxxxxxx> 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
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