Messages in this thread | | | Subject | Re: [PATCH] gpio: Do not accept gpio chip additions before gpiolib initialization | From | Guenter Roeck <> | Date | Wed, 30 Mar 2016 02:16:02 -0700 |
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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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