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Date:   Sat, 12 Aug 2023 17:19:28 +0800
From:   Wang Jinchao <wangjinchao@xfusion.com>
To:     Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>,
        David Airlie <airlied@gmail.com>,
        Daniel Vetter <daniel@ffwll.ch>,
        <intel-gfx@lists.freedesktop.org>,
        <dri-devel@lists.freedesktop.org>, <linux-kernel@vger.kernel.org>
CC:     <stone.xulei@xfusion.com>
Subject: [PATCH] drm/i915: Fix Kconfig error for CONFIG_DRM_I915
Message-ID: <ZNdOoHvIg7HXh7Gg@fedora>
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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.

Signed-off-by: Wang Jinchao <wangjinchao@xfusion.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 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
-- 
2.40.0