On Tuesday, November 8, 2016 10:46:07 AM CET Ilia Mirkin wrote:
> > diff --git a/drivers/gpu/drm/nouveau/Kconfig
> > b/drivers/gpu/drm/nouveau/Kconfig
> > index 78631fb61adf..715cd6f4dc31 100644
> > --- a/drivers/gpu/drm/nouveau/Kconfig
> > +++ b/drivers/gpu/drm/nouveau/Kconfig
> > @@ -46,6 +46,14 @@ config NOUVEAU_DEBUG
> > The paranoia and spam levels will add a lot of extra checks which
> > may potentially slow down driver operation.
> >
> > +config DRM_NOUVEAU_LED
> > + bool "Support for logo LED"
> > + depends on DRM_NOUVEAU && LEDS_CLASS
> > + depends on !(DRM_NOUVEAU=y && LEDS_CLASS=m)
> > + help
> > + Say Y here to enabling controlling the brightness of the
> > + LED behind NVIDIA logo on certain Titan cards.
>
> This is a very odd restriction... could this be written as
>
> depends on DRM_NOUVEAU
> select LEDS_CLASS
>
> Or will that not flip the LEDS_CLASS from m to y in case
> DRM_NOUVEAU=y? If not, is there a way to cause that to happen?
Using 'select' on user-selectable symbols risks introducing
circular dependencies.
> Separately, perhaps we should just drop this LEDS_CLASS select into
> DRM_NOUVEAU? We've tended to avoid adding tons of options.
My first attempt was to add "depends on LEDS_CLASS || !LEDS_CLASS"
to DRM_NOUVEAU, which led to one long circle:
drivers/usb/Kconfig:39:error: recursive dependency detected!
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/usb/Kconfig:39: symbol USB is selected by MOUSE_APPLETOUCH
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/input/mouse/Kconfig:187: symbol MOUSE_APPLETOUCH depends on INPUT
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/input/Kconfig:8: symbol INPUT is selected by VT
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/tty/Kconfig:12: symbol VT is selected by FB_STI
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/video/fbdev/Kconfig:669: symbol FB_STI depends on FB
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/video/fbdev/Kconfig:5: symbol FB is selected by DRM_KMS_FB_HELPER
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/drm/Kconfig:42: symbol DRM_KMS_FB_HELPER depends on
DRM_KMS_HELPER
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/drm/Kconfig:36: symbol DRM_KMS_HELPER is selected by DRM_NOUVEAU
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/drm/nouveau/Kconfig:1: symbol DRM_NOUVEAU depends on LEDS_CLASS
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/leds/Kconfig:16: symbol LEDS_CLASS is selected by OMAP_DEBUG_LEDS
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
arch/arm/plat-omap/Kconfig:19: symbol OMAP_DEBUG_LEDS depends on NEW_LEDS
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/leds/Kconfig:8: symbol NEW_LEDS is selected by ATH9K_HTC
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/net/wireless/ath/ath9k/Kconfig:158: symbol ATH9K_HTC depends on USB
Tue, 08 Nov 2016 11:49:44 +0100 build/0x3053A542_defconfig warnings
drivers/usb/Kconfig:39:error: recursive dependency detected!
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/usb/Kconfig:39: symbol USB is selected by MOUSE_APPLETOUCH
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/input/mouse/Kconfig:187: symbol MOUSE_APPLETOUCH depends on INPUT
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/input/Kconfig:8: symbol INPUT is selected by VT
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/tty/Kconfig:12: symbol VT is selected by FB_STI
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/video/fbdev/Kconfig:669: symbol FB_STI depends on FB
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/video/fbdev/Kconfig:5: symbol FB is selected by DRM_KMS_FB_HELPER
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/drm/Kconfig:42: symbol DRM_KMS_FB_HELPER depends on
DRM_KMS_HELPER
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/drm/Kconfig:36: symbol DRM_KMS_HELPER is selected by DRM_NOUVEAU
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/gpu/drm/nouveau/Kconfig:1: symbol DRM_NOUVEAU depends on LEDS_CLASS
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/leds/Kconfig:16: symbol LEDS_CLASS is selected by OMAP_DEBUG_LEDS
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
arch/arm/plat-omap/Kconfig:19: symbol OMAP_DEBUG_LEDS depends on NEW_LEDS
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/leds/Kconfig:8: symbol NEW_LEDS is selected by ATH9K_HTC
For a resolution refer to Documentation/kbuild/kconfig-language.txt
subsection "Kconfig recursive dependency limitations"
drivers/net/wireless/ath/ath9k/Kconfig:158: symbol ATH9K_HTC depends on USB
The underlying problem is that we already have a number of other
symbols that either have "depends on LEDS_CLASS" or
"select LEDS_CLASS". To clean that up properly, we should either
make the symbol itself hidden and only select it from other drivers,
or use "depends on LEDS_CLASS" everywhere.
Another option is to use the IS_REACHABLE() macro instead of IS_ENABLED()
in the header file, to stub out the calls into the new file, but
that can be a bit confusing.
Arnd
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