Re: [PATCH] drivers: depend on instead of select BACKLIGHT_CLASS_DEVICE and ACPI_VIDEO

[Michael Ellerman]

On Wed, 2014-10-29 at 09:54 +0200, Jani Nikula wrote:
> On Wed, 29 Oct 2014, Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote:
> > On Tue, 2014-10-28 at 13:29 -0700, Randy Dunlap wrote:
> >> On 10/27/14 06:13, Tomi Valkeinen wrote:
> >> > I also think the 'depends on BACKLIGHT_CLASS_DEVICE ||
> >> > BACKLIGHT_CLASS_DEVICE=n' pattern is quite... interesting (i.e. sounds
> >> > like a hack to me =).
> >> 
> >> It does exactly what is needed and it is used in many places in kernel
> >> Kconfig files.
> >
> > Is there any reason you can't do:
> >
> >   depends on BACKLIGHT_CLASS_DEVICE != m
> 
> That's not the same thing. The FOO || FOO=n allows for all options, but
> forbids it being a module when the option depending on it is
> built-in.

OK right. Because "BAR depends on FOO" is short for "depends on FOO=y || FOO=m",
but also adds the implicit condition that if FOO=m then BAR must also be m.

Thanks for clueing me in.

cheers


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