On Wed, 29 Mar 2017, Tobias Regnery <tobias.regnery@xxxxxxxxx> wrote: > With CONFIG_ACPI=n and CONFIG_BACKLIGHT_CLASS_DEVICE=n we see the following > link error in the i915 driver: > > drivers/built-in.o: In function 'intel_backlight_device_register': > (.text+0x2a921d): undefined reference to 'backlight_device_register' > > Fix this by removing the condition on ACPI from the appropriate select > statement. The right fix for the build problem is to add empty stub functions for BACKLIGHT_CLASS_DEVICE=n in include/linux/backlight.h. I'm frankly surprised nobody's done that yet. It's another question whether we should support and select backlight for ACPI=n, and yet another question whether we should support ACPI=n. Also, selecting BACKLIGHT_CLASS_DEVICE is fundamentally broken, but people aren't interested [1]. BR, Jani. [1] http://mid.mail-archive.com/1413580403-16225-1-git-send-email-jani.nikula@xxxxxxxxx > > Signed-off-by: Tobias Regnery <tobias.regnery@xxxxxxxxx> > --- > drivers/gpu/drm/i915/Kconfig | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig > index a5cd5dacf055..532df4bb9283 100644 > --- a/drivers/gpu/drm/i915/Kconfig > +++ b/drivers/gpu/drm/i915/Kconfig > @@ -15,7 +15,7 @@ config DRM_I915 > # i915 depends on ACPI_VIDEO when ACPI is enabled > # but for select to work, need to select ACPI_VIDEO's dependencies, ick > select BACKLIGHT_LCD_SUPPORT if ACPI > - select BACKLIGHT_CLASS_DEVICE if ACPI > + select BACKLIGHT_CLASS_DEVICE > select INPUT if ACPI > select ACPI_VIDEO if ACPI > select ACPI_BUTTON if ACPI -- Jani Nikula, Intel Open Source Technology Center _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
