Re: [Intel-gfx] [PATCH 1/7] drm/i915/hwmon: Add HWMON infrastructure

[Guenter Roeck <linux@roeck-us.net>]

On Tue, Aug 23, 2022 at 12:46:14PM +0300, Jani Nikula wrote:
[ ... ]
> >> 
> >> So why not do this in i915 Kconfig:
> >> 
> >> config DRM_I915
> >> 	...
> >> 	depends on HWMON || HWMON=n
> > With this change I am getting recursive dependancy error when I run make 
> > oldconfig
> >
> > badal@bnilawar-desk1:~/workspace/wp3/drm-tip$ make oldconfig
> >    HOSTCC  scripts/basic/fixdep
> >    HOSTCC  scripts/kconfig/conf.o
> >    HOSTCC  scripts/kconfig/confdata.o
> >    HOSTCC  scripts/kconfig/expr.o
> >    LEX     scripts/kconfig/lexer.lex.c
> >    YACC    scripts/kconfig/parser.tab.[ch]
> >    HOSTCC  scripts/kconfig/lexer.lex.o
> >    HOSTCC  scripts/kconfig/menu.o
> >    HOSTCC  scripts/kconfig/parser.tab.o
> >    HOSTCC  scripts/kconfig/preprocess.o
> >    HOSTCC  scripts/kconfig/symbol.o
> >    HOSTCC  scripts/kconfig/util.o
> >    HOSTLD  scripts/kconfig/conf
> > drivers/gpu/drm/i915/Kconfig:2:error: recursive dependency detected!
> > drivers/gpu/drm/i915/Kconfig:2: symbol DRM_I915 depends on HWMON
> > drivers/hwmon/Kconfig:6:        symbol HWMON is selected by EEEPC_LAPTOP
> > drivers/platform/x86/Kconfig:332:       symbol EEEPC_LAPTOP depends on INPUT
> > drivers/input/Kconfig:8:        symbol INPUT is selected by DRM_I915
> > For a resolution refer to Documentation/kbuild/kconfig-language.rst
> > subsection "Kconfig recursive dependency limitations"
> 
> *sigh*
> 
>   Note:
> 	select should be used with care. select will force
> 	a symbol to a value without visiting the dependencies.
> 	By abusing select you are able to select a symbol FOO even
> 	if FOO depends on BAR that is not set.
> 	In general use select only for non-visible symbols
> 	(no prompts anywhere) and for symbols with no dependencies.
> 	That will limit the usefulness but on the other hand avoid
> 	the illegal configurations all over.
> 
Agreed. HWMON should not be selected anywhere. Unfortunately it is, and
drm is no exception. It is selected by DRM_RADEON and DRM_AMDGPU.
Maybe just select it in DRM_I915 as well after all; in practice it won't
make a difference.

Guenter