[U-Boot] [PATCH v2 21/44] Convert CONFIG_SPL_GPIO_SUPPORT to Kconfig

From: Simon Glass <sjg@chromium.org>
To: u-boot@lists.denx.de
Subject: [U-Boot] [PATCH v2 21/44] Convert CONFIG_SPL_GPIO_SUPPORT to Kconfig
Date: Mon, 5 Sep 2016 19:04:45 -0600	[thread overview]
Message-ID: <CAPnjgZ0-aV7UgEpv0nmzfcM6yeT=939J1W+G+7wPFdad=hgfYg@mail.gmail.com> (raw)
In-Reply-To: <CAK7LNATrd4TJgTTQAgx3qXZqDiAyDp5awH8pJECtREHAjKVDRA@mail.gmail.com>

Hi Masahiro,

On 4 September 2016 at 20:40, Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
> 2016-09-02 23:35 GMT+09:00 Tom Rini <trini@konsulko.com>:
>
>>> >> diff --git a/arch/arm/mach-exynos/Kconfig b/arch/arm/mach-exynos/Kconfig
>>> >> index c25fcf3..d4a5bc9 100644
>>> >> --- a/arch/arm/mach-exynos/Kconfig
>>> >> +++ b/arch/arm/mach-exynos/Kconfig
>>> >> @@ -61,6 +61,9 @@ endif
>>> >>
>>> >>  if ARCH_EXYNOS5
>>> >>
>>> >> +config SPL_GPIO_SUPPORT
>>> >> +       default y
>>> >> +
>>> >
>>> >
>>> > As we discussed before,
>>> > we decided to not do this.
>>>
>>> Tom was keen to avoid changing every defconfig file. It is there
>>> another way to express common defaults?
>>
>> I was thinking in the Kconfig with the entry for SPL_GPIO_SUPPORT, for
>> optional stuff and select in the board, etc, Kconfig for non-optional
>> stuff.  Now, I realize that optional vs non-optional is more the domain
>> of the individual SoC custodians, so we'll have some clean up afterwards
>> that isn't on you (well, aside from the SoCs you know like rockchip ;)).
>
> config SPL_GPIO_SUPPORT
>        default y
>
> is incorrect because it could violate
> the dependency in the proper Kconfig entry in spl/Kconfig.

But only if options depended on by this are not set, right?

>
>
>
>
> Basically, we are supposed to use "select FOO" when it is mandatory,
> or add CONFIG_FOO=y in a defconfig when the board wants it, but
> can still make it optional.

Yes, but this is not mandatory. It is a default, and some boards will
unset it. I did this in response to Tom's comment about trying to cut
down the defconfig patch size.

>
>
> I know our pain comes from that "include" is not supported by Kconfig.

How would that help? Why don't we implement it?

>
> What I can suggest now is:
>
>
>
> [1]  Add ARCH_WANT_* to specify a SoC-common default.
>
>
>        config SPL_GPIO_SUPPORT
>                 bool "GPIO support for SPL"
>                 default  ARCH_WANT_SPL_GPIO_SUPPORT
>
>
>        config ARCH_WANT_SPL_GPIO_SUPPORT
>                 bool
>
>
>        config ARCH_EXYNOS5
>                select ARCH_WANT_SPL_GPIO_SUPPORT
>
>
> Linux used to have ARCH_WANT_OPTIONAL_GPIOLIB to do similar things.
> (they stopped this way, though)
>
>
>
> [2] Support multi boards with one defconfig
>     (barebox supports multi-platform like Linux does.)
>
>
> [3] use pre-processor to support #include <...>
>
>
>
>
>
> BTW, SPL_GPIO_SUPPORT is optional in this case?
>
> U-Boot proper supports a command line interface,
> while SPL is usually run in a non-interactive mode.
>
> So, what SPL needs is generally mandatory,
> so we can "select" it,  I guess.

I found a lot of cases where 90% of the boards with the same SoC  had
the same setting for this (and a few other) options, but some boards
did not. So I did not want to use select, since then it is impossible
to unselect.

This series is actually really tricky. I'm looking forward to putting
it to bed. We need to make these conversions easier.

Regards,
Simon