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    SubjectRe: [PATCH] gpio: Do not accept gpio chip additions before gpiolib initialization
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    On 03/30/2016 01:37 AM, Alexandre Courbot wrote:
    > On Wed, Mar 30, 2016 at 3:20 AM, Guenter Roeck <linux@roeck-us.net> wrote:
    >> Since commit ff2b13592299 ("gpio: make the gpiochip a real device"),
    >> attempts to add a gpio chip prior to gpiolib initialization cause the
    >> system to crash. Dump a warning to the console and return an error
    >> if the situation is encountered.
    >
    > Mmm I see the problem but this could seriously delay the availability
    > of some GPIOs that are useful for early system boot.
    >
    > I have not followed the GPIO device patches as closely as I should
    > have, but shouldn't you be able to register a GPIO chip without
    > immediately presenting it to user-space, for internal kernel needs? If
    > gpiolib is not initialized, then device-related operations would be
    > skipped, and gpiolib_dev_init() could then parse the list of
    > registered chips and fix them up when it gets called.
    >
    > Again, I'm speaking without real knowledge here, but that pattern
    > seems more resilent to me.
    >
    You are absolutely right, but my knowledge of gpiolib is not good enough
    to make that change. See this as a band-gap; it is better than just crashing.

    Guenter

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