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

["Nilawar, Badal" <badal.nilawar@intel.com>]

On 23-08-2022 19:05, Jani Nikula wrote:
> On Tue, 23 Aug 2022, Guenter Roeck <linux@roeck-us.net> wrote:
>> 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.
> 
> And I guess everyone just does what I'm about to do now, throw my hands
> up in the air in disgust and resignation. :p
How about sticking to existing approach only. In my previous response I 
mentioned that for combo which we want to reject CONFIG_HWMON=m && 
CONFIG_DRM_I915=y combo i915_hwmon.o is not getting build.
It is only getting build for below combos
CONFIG_HWMON=m && CONFIG_DRM_I915=y
CONFIG_HWMON=m && CONFIG_DRM_I915=m
CONFIG_HWMON=y && CONFIG_DRM_I915=m
Regards,
Badal
> 
> BR,
> Jani.
> 
> 
>