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

On Wed, 2014-10-29 at 09:54 +0200, Jani Nikula wrote:

On Wed, 29 Oct 2014, Michael Ellerman [off-list ref] wrote:

quoted

On Tue, 2014-10-28 at 13:29 -0700, Randy Dunlap wrote:

quoted

On 10/27/14 06:13, Tomi Valkeinen wrote:

quoted

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