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    SubjectRe: [PATCH v3] gpio: interrupt consistency check for OF GPIO IRQs
    Hi everyone,

    [jumping in on an old discussion]

    On 09/09/2013 06:19 PM, Mark Brown wrote:
    > On Wed, Sep 04, 2013 at 02:16:36PM -0600, Stephen Warren wrote:
    >> On 09/04/2013 03:05 AM, Lars Poeschel wrote:
    >
    >>> The driver that tries to use the GPIO requested by this patch before HAS to
    >>> fail. This is exactly the intention of this patch. We don't want the GPIO to
    >>> be requested any more, if it is used as an interrupt pin.
    >
    >> That will break existing drivers. There are drivers that request the
    >> same GPIO and IRQ. IIRC, the SDHCI CD (Card Detect) GPIO is requested
    >> that way.
    >
    > Yes, plus input devices and audio jack detection among others. This
    > pattern is very common if the GPIO is actually being used as a GPIO, an
    > edge triggered interrupt is used to flag when something happens and the
    > state is determined by reading the GPIO state (often with some
    > debounce).

    I actually came across this thread while looking for an answer to the
    following (apparently trivial) question:

    If you were to write a new driver & binding, what would be, in general,
    the recommended DT binding for a cascade interrupt controller (or any
    other peripheral, for that matter), which is connected through a GPIO
    (to be used as IRQ)?

    a) Through gpios = <&gpio0 N>
    b) through interrupt-parent = <&gpio0> & interrupts <N
    IRQ_TYPE_LEVEL_LOW>, or
    c) both?

    Thanks!
    Gerlando


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