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Re: [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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[PATCH] gpio: Do not accept gpio chip additions before gpiolib initialization Guenter Roeck <linux@roeck-us.net> - 2016-03-29 20:30 +0200
  Re: [PATCH] gpio: Do not accept gpio chip additions before gpiolib initialization Alexandre Courbot <gnurou@gmail.com> - 2016-03-30 10:40 +0200
    Re: [PATCH] gpio: Do not accept gpio chip additions before gpiolib  initialization Guenter Roeck <linux@roeck-us.net> - 2016-03-30 11:20 +0200
      Re: [PATCH] gpio: Do not accept gpio chip additions before gpiolib initialization Alexandre Courbot <gnurou@gmail.com> - 2016-03-31 08:00 +0200
        Re: [PATCH] gpio: Do not accept gpio chip additions before gpiolib  initialization Guenter Roeck <linux@roeck-us.net> - 2016-03-31 14:50 +0200
  Re: [PATCH] gpio: Do not accept gpio chip additions before gpiolib  initialization Guenter Roeck <linux@roeck-us.net> - 2016-03-31 18:00 +0200

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