On Fri, 24 Apr 2015, Jim Davis jim.epost@gmail.com wrote:

Building with the attached random configuration file,

warning: (SND_SOC_INTEL_BYTCR_RT5640_MACH && SND_SOC_INTEL_CHT_BSW_RT5672_MACH && SND_SOC_INTEL_CHT_BSW_RT5645_MACH) selects SND_SST_IPC_ACPI which has unmet direct dependencies (SOUND && !M68K && !UML && SND && SND_SOC && ACPI)

drivers/built-in.o: In function `intel_backlight_register': (.text+0xfaafa): undefined reference to `backlight_device_register' drivers/built-in.o: In function `intel_backlight_unregister': (.text+0xfab7d): undefined reference to `backlight_device_unregister'

This is because you end up with:

CONFIG_DRM_I915=y CONFIG_BACKLIGHT_CLASS_DEVICE=m

which is due to i915 selecting, not depending on, backlight class device. But we can't just switch to depend in i915, because it creates circular dependencies across the board, and to fix that we end up with a patch I proposed about six months ago [1]. See the discussion there, and also [2]. I think switching from select to depend on is the technically right fix, but I don't have the time to fight this across all affected subsystems.

BR, Jani.

[1] http://mid.gmane.org/1413580403-16225-1-git-send-email-jani.nikula@intel.com [2] http://mid.gmane.org/87wq1wot9b.fsf@intel.com