Re: [PATCH] mfd: Combine MFD_SUPPORT and MFD_CORE

[Arnd Bergmann <arnd@arndb.de>]

On Monday 29 August 2011, Luciano Coelho wrote:
> From: Randy Dunlap <rdunlap@xenotime.net>
> 
> Combine MFD_SUPPORT (which only enabled the remainder of the MFD
> menu) and MFD_CORE.  This allows other drivers to select MFD_CORE
> without needing to also select MFD_SUPPORT, which fixes some
> kconfig unmet dependency warnings.  Modeled after I2C kconfig.
> 
> [Forward-ported to 3.1-rc4.  This fixes a warning when some drivers,
> such as RADIO_WL1273, are selected, but MFD_SUPPORT is not. -- Luca]
> 
> Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
> Reported-by: Johannes Berg <johannes@sipsolutions.net>
> Cc: Jean Delvare <khali@linux-fr.org>
> Cc: Tony Lindgren <tony@atomide.com>
> Cc: Grant Likely <grant.likely@secretlab.ca>
> Signed-off-by: Luciano Coelho <coelho@ti.com>
> ---
> 
> I guess this should fix the problem.  I've simple forward-ported
> Randy's patch to the latest mainline kernel.  I don't know via which
> tree this should go in, though.
> 
> NOTE: I have not tested this very thoroughly.  But at least
> omap2plus stuff seems to work okay with this change.  MFD_SUPPORT is
> also selected by a couple of "tile" platforms defconfigs, but I guess
> the Kconfig system should take care of it.

Doing this is a good idea, but incidentally I have just spent some time
with the same problem and ended up with a solution that I like better,
which is removing CONFIG_MFD_SUPPORT altogether.

The point is that there is no use enabling MFD_CORE if you don't also
enable any of the specific drivers. MFD_SUPPORT was added as a 'menuconfig'
before we had Kconfig warn about broken dependencies, so everything was
fine. Since Kconfig now issues the warnings, I think it would be better
to just turn the MFD menu into a plain 'menu' and remove all the
'depends on MFD_SUPPORT' and 'select MFD_SUPPORT' lines from the other
Kconfig files.

	Arnd