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    SubjectRe: [RFC PATCH v2 00/13] arm/tegra: Initialize GPIO & pinmux from DT
    Date
    On Tuesday 16 August 2011, Stephen Warren wrote:
    > One issue here: There isn't always a single gpio/pinmux parent; as a
    > concrete example, the ALSA/ASoC driver for Tegra+WM8903 uses GPIOs both
    > from Tegra itself, and from the WM8903 audio codec.
    >
    > I could imagine the same being true in basically any case where one
    > device uses N GPIOs (e.g. SD controller with power, change-detect,
    > and read-only GPIOs; some could easily come from the SoC and some
    > from a GPIO expander).
    >
    > I'm not quite so sure that multiple parents would be useful for pinmux,
    > but I wouldn't say that it was impossible...

    Hmm, how common do you think the example is?

    It it's just a very rare case, we can still special-case it by
    introducing fake subdevices for the Tegra+WM8903 driver, each of
    which has only one gpio-parent. This is ugly but keeps the special
    case to the rare devices.

    If we can expect more than a handful of these, we probably need
    a better design for the binding, which will cause a burden for
    all drivers.

    Arnd


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