On 30.03.17, Jani Nikula wrote:
On Wed, 29 Mar 2017, Tobias Regnery tobias.regnery@gmail.com 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.
Thanks for the advice, I will try to come up with a patch.
-- Tobias
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@in...
Signed-off-by: Tobias Regnery tobias.regnery@gmail.com
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