On Thu, Sep 12, 2019 at 11:29:00AM +0200, Arnd Bergmann wrote:

> Generally speaking, the way that works best is

> config SUBSYS_DRIVER_FOO
>        tristate "SUBSYS support for FOO platform"
>        depends on ARCH_FOO || COMPILE_TEST
>        depends on SUBSYS
>        default "m" if ARCH_FOO

> This means it's enabled as a loadable module by default (use
> default "y" instead where necessary) as long as the platform
> is enabled, but an x86 allmodconfig build also includes it
> because of COMPILE_TEST, while any configuration without
> ARCH_FOO that is not compile-testing cannot enable it.

Indeed, though we shouldn't be adding any default m/y to things
that don't already default on.