On Mon, 14 Aug 2023, Wang Jinchao <wangjinchao@xxxxxxxxxxx> wrote: > On Mon, Aug 14, 2023 at 10:26:45AM +0300, Jani Nikula wrote: >> On Sat, 12 Aug 2023, Wang Jinchao <wangjinchao@xxxxxxxxxxx> wrote: >> > When CONFIG_DRM_I915 is set to 'y' and CONFIG_BACKLIGHT_CLASS_DEVICE >> > is set to 'm', we encountered an ld.lld error during the build process: >> > >> > ld.lld: error: undefined symbol: backlight_device_get_by_name >> > >>> referenced by intel_backlight.c:955 >> > >>> vmlinux.o:(intel_backlight_device_register) >> > >> > ld.lld: error: undefined symbol: backlight_device_register >> > >>> referenced by intel_backlight.c:971 >> > >>> vmlinux.o:(intel_backlight_device_register) >> > >> > ld.lld: error: undefined symbol: backlight_device_unregister >> > >>> referenced by intel_backlight.c:999 >> > >>> vmlinux.o:(intel_backlight_device_unregister) >> > >> > This issue occurred because intel_backlight_device_register and >> > intel_backlight_device_unregister were enclosed within >> > However, according to Kconfig, CONFIG_DRM_I915 will select >> > BACKLIGHT_CLASS_DEVICE only if ACPI is enabled. >> > This led to an error, which can be resolved by removing the >> > conditional statements related to ACPI. >> >> The real fix is to use >> >> depends on BACKLIGHT_CLASS_DEVICE || BACKLIGHT_CLASS_DEVICE=n > it works. >> >> but in order to do that, you need to change a lot of places to depend > Why, what are the other places? Generally when you have a mixture of depends on and select on a kconfig symbol, you'll eventually end up with dependency problems. BR, Jani. >> on, not select BACKLIGHT_CLASS_DEVICE, because otherwise you end up with > got it. >> other dependency issues. >> >> BR, >> Jani. >> >> > >> > Signed-off-by: Wang Jinchao <wangjinchao@xxxxxxxxxxx> >> > --- >> > 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 01b5a8272a27..5003de921bf7 100644 >> > --- a/drivers/gpu/drm/i915/Kconfig >> > +++ b/drivers/gpu/drm/i915/Kconfig >> > @@ -24,7 +24,7 @@ config DRM_I915 >> > select IRQ_WORK >> > # i915 depends on ACPI_VIDEO when ACPI is enabled >> > # but for select to work, need to select ACPI_VIDEO's dependencies, ick >> > - select BACKLIGHT_CLASS_DEVICE if ACPI >> > + select BACKLIGHT_CLASS_DEVICE >> > select INPUT if ACPI >> > select X86_PLATFORM_DEVICES if ACPI >> > select ACPI_WMI if ACPI >> >> -- >> Jani Nikula, Intel Open Source Graphics Center -- Jani Nikula, Intel Open Source Graphics Center
