On Sat, Oct 18, 2014 at 12:13:23AM +0300, Jani Nikula wrote: > Documentation/kbuild/kconfig-language.txt warns to use select with care, > and in general use select only for non-visible symbols and for symbols > with no dependencies, because select will force a symbol to a value > without visiting the dependencies. > > Select has become particularly problematic, interdependently, with the > BACKLIGHT_CLASS_DEVICE and ACPI_VIDEO configs. For example: > > scripts/kconfig/conf --randconfig Kconfig > KCONFIG_SEED=0x48312B00 > warning: (DRM_RADEON && DRM_NOUVEAU && DRM_I915 && DRM_GMA500 && > DRM_SHMOBILE && DRM_TILCDC && FB_BACKLIGHT && FB_MX3 && USB_APPLEDISPLAY > && FB_OLPC_DCON && ASUS_LAPTOP && SONY_LAPTOP && THINKPAD_ACPI && > EEEPC_LAPTOP && ACPI_CMPC && SAMSUNG_Q10) selects BACKLIGHT_CLASS_DEVICE > which has unmet direct dependencies (HAS_IOMEM && BACKLIGHT_LCD_SUPPORT) > warning: (DRM_RADEON && DRM_NOUVEAU && DRM_I915 && DRM_GMA500 && > DRM_SHMOBILE && DRM_TILCDC && FB_BACKLIGHT && FB_MX3 && USB_APPLEDISPLAY > && FB_OLPC_DCON && ASUS_LAPTOP && SONY_LAPTOP && THINKPAD_ACPI && > EEEPC_LAPTOP && ACPI_CMPC && SAMSUNG_Q10) selects BACKLIGHT_CLASS_DEVICE > which has unmet direct dependencies (HAS_IOMEM && BACKLIGHT_LCD_SUPPORT) > > With tristates it's possible to end up selecting FOO=y depending on > BAR=m in the config, which gets discovered at build time, not config > time, like reported in the thread referenced below. > > Do the following to fix the dependencies: > > * Depend on instead of select BACKLIGHT_CLASS_DEVICE everywhere. Drop > select BACKLIGHT_LCD_SUPPORT in such cases, as it's a dependency of > BACKLIGHT_CLASS_DEVICE. > > * Remove config FB_BACKLIGHT altogether, and replace it with a > dependency on BACKLIGHT_CLASS_DEVICE. All configs selecting > FB_BACKLIGHT select or depend on FB anyway, so we can simplify. > > * Depend on (ACPI && ACPI_VIDEO) || ACPI=n in several places instead of > selecting ACPI_VIDEO and a number of its dependencies if ACPI is > enabled. This is tied to backlight, as ACPI_VIDEO depends on > BACKLIGHT_CLASS_DEVICE. > > * Replace a couple of select INPUT/VT with depends as it seemed to be > necessary. > > Reference: > http://lkml.kernel.org/r/ca+r1zhhmt4drwtf6mbrqo5eqxwx+lxcqh15vsu_d9wpftlh...@mail.gmail.com > Reported-by: Jim Davis <[email protected]> > Cc: Randy Dunlap <[email protected]> > Cc: David Airlie <[email protected]> > Cc: Daniel Vetter <[email protected]> > Cc: Greg Kroah-Hartman <[email protected]> > Cc: Darren Hart <[email protected]> > Cc: Laurent Pinchart <[email protected]> > Cc: Benjamin Herrenschmidt <[email protected]> > Cc: Jens Frederich <[email protected]> > Cc: Daniel Drake <[email protected]> > Cc: Jon Nettleton <[email protected]> > Cc: Jean-Christophe Plagniol-Villard <[email protected]> > Cc: Tomi Valkeinen <[email protected]> > Signed-off-by: Jani Nikula <[email protected]>
As for the drivers/platform/x86/Kconfig: Acked-by: Darren Hart <[email protected]> Thanks, -- Darren Hart Intel Open Source Technology Center -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
