Re: [PATCH] gpio: Fix OF build problem on UM

[Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>]

On Fri, Aug 19, 2016 at 10:53 AM, Linus Walleij
<linus.walleij@xxxxxxxxxx> wrote:
> On Wed, Aug 17, 2016 at 11:03 AM, Geert Uytterhoeven
> <geert@xxxxxxxxxxxxxx> wrote:
>> On Tue, Aug 16, 2016 at 10:06 AM, Linus Walleij
>> <linus.walleij@xxxxxxxxxx> wrote:
>>> The UserMode (UM) Linux build was failing in gpiolib-of as it requires
>>> ioremap()/iounmap() to exist, which is absent from UM. The non-existence
>>> of IO memory is negatively defined as CONFIG_NO_IOMEM so put a reverse
>>> dependency on !NO_IOMEM for OF_GPIO to fix the build.
>>>
>>> Cc: stable@xxxxxxxxxxxxxxx
>>> Reported-by: kbuild test robot <fengguang.wu@xxxxxxxxx>
>>> Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
>>> ---
>>>  drivers/gpio/Kconfig | 1 +
>>>  1 file changed, 1 insertion(+)
>>>
>>> diff --git a/drivers/gpio/Kconfig b/drivers/gpio/Kconfig
>>> index 98dd47a30fc7..a6026f2fe7f5 100644
>>> --- a/drivers/gpio/Kconfig
>>> +++ b/drivers/gpio/Kconfig
>>> @@ -50,6 +50,7 @@ config GPIO_DEVRES
>>>  config OF_GPIO
>>>         def_bool y
>>>         depends on OF
>>> +       depends on !NO_IOMEM
>>
>> depends on HAS_IOMEM?
>
> Apparently not, and that is the scary thing.
>
> HAS_IOMEM depends on !NO_IOMEM indeed but
> it also selects GENERIC_IO, and AFAICT there are
> some configs out there in the intersection between,
> that have IOMEM but are not using GENERIC_IO,
> tell me if I'm wrong :/

lib/Kconfig:

    config HAS_IOMEM
            bool
            depends on !NO_IOMEM
            select GENERIC_IO
            default y

Hence if NO_IOMEM is not set, HAS_IOMEM and GENERIC_IO are always set.

UML selects GENERIC_IO, but not HAS_IOMEM (it sets NO_IOMEM).

Perhaps you're confusing GENERIC_IO with GENERIC_IOMAP?

Gr{oetje,eeting}s,

                        Geert

--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds
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