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

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

On 23-08-2022 20:11, Jani Nikula wrote:
> On Tue, 23 Aug 2022, "Nilawar, Badal" <badal.nilawar@intel.com> wrote:
>> 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
> 
> Then please hide the IS_REACHABLE() within i915_hwmon.h and add stubs as
> is customary. Let's not clutter high level driver code with some random
> #if directives.

Thanks, I will resolve this and float the new series.

Regards,
Badal
> 
> BR,
> Jani.
> 
> 
>> Regards,
>> Badal
>>>
>>> BR,
>>> Jani.
>>>
>>>
>>>
>