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From:   Arnd Bergmann <arnd@kernel.org>
To:     dri-devel@lists.freedesktop.org,
        Jani Nikula <jani.nikula@linux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@intel.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>
Cc:     linux-fbdev@vger.kernel.org, intel-gfx@lists.freedesktop.org,
        Arnd Bergmann <arnd@arndb.de>,
        Matthew Auld <matthew.auld@intel.com>,
        Zhenyu Wang <zhenyuw@linux.intel.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>,
        linux-kernel@vger.kernel.org
Subject: [PATCH 3/3] [v2] i915: fix backlight configuration issue
Date:   Wed, 27 Oct 2021 15:27:14 +0200
Message-Id: <20211027132732.3993279-3-arnd@kernel.org>
In-Reply-To: <20211027132732.3993279-1-arnd@kernel.org>
References: <20211027132732.3993279-1-arnd@kernel.org>
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From: Arnd Bergmann <arnd@arndb.de>

The i915 driver can use the backlight subsystem as an option, and usually
selects it when CONFIG_ACPI is set. However it is possible to configure
a kernel with modular backlight classdev support and a built-in i915
driver, which leads to a linker error:

drivers/gpu/drm/i915/display/intel_panel.o: In function `intel_backlight_device_register':
intel_panel.c:(.text+0x2f58): undefined reference to `backlight_device_register'
drivers/gpu/drm/i915/display/intel_panel.o: In function `intel_backlight_device_unregister':
intel_panel.c:(.text+0x2fe4): undefined reference to `backlight_device_unregister'

Change i915 to just 'depends on' for both BACKLIGHT_CLASS_DEVICE
and ACPI_VIDEO, which avoids a lot of the problems.

Link: https://lore.kernel.org/all/20200108140227.3976563-1-arnd@arndb.de/
Link: https://lore.kernel.org/all/20200417155553.675905-1-arnd@arndb.de/
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
This change depends on cleaning up drivers/video/fbdev to no longer
'select' I2C and BACKLIGHT_CLASS_DEVICE, otherwise it causes
dependency loops.
---
 drivers/gpu/drm/i915/Kconfig | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/i915/Kconfig b/drivers/gpu/drm/i915/Kconfig
index 84b6fc70cbf5..f427e6d50d9b 100644
--- a/drivers/gpu/drm/i915/Kconfig
+++ b/drivers/gpu/drm/i915/Kconfig
@@ -3,6 +3,8 @@ config DRM_I915
 	tristate "Intel 8xx/9xx/G3x/G4x/HD Graphics"
 	depends on DRM
 	depends on X86 && PCI
+	depends on ACPI_VIDEO || !ACPI
+	depends on BACKLIGHT_CLASS_DEVICE || !BACKLIGHT_CLASS_DEVICE
 	select INTEL_GTT
 	select INTERVAL_TREE
 	# we need shmfs for the swappable backing store, and in particular
@@ -16,10 +18,6 @@ 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 INPUT if ACPI
-	select ACPI_VIDEO if ACPI
-	select ACPI_BUTTON if ACPI
 	select SYNC_FILE
 	select IOSF_MBI
 	select CRC32
-- 
2.29.2