[PATCH v2] ACPI / video: Disable native backlight on Samsung Series 9 laptops

[Jens Reyer <jens.reyer@gmail.com>]

Add video_disable_native_backlight quirk for SAMSUNG 900X3C/900X3D/
900X3E/900X4C/900X4D laptops.

The native intel backlight controls do not work correctly on SAMSUNG
Series 9 (900X3C/900X3D/900X3E/900X4C/900X4D) laptops:
One machine has an completely dimmed (= black) display after boot at the
GDM login screen and brightness controls work only between 0 and 5%
(= no effect).
Another machine has the same brightness control issues if an external
HDMI monitor is or gets connected, although the initial brightness is
ok.
After login to Gnome both machines always work fine.

Tested on both machines.

Bug-Link: https://bugs.freedesktop.org/show_bug.cgi?id=87286
Bug-Link: https://bugs.debian.org/772440
Signed-off-by: Jens Reyer <jens.reyer@gmail.com>
---
 drivers/acpi/video.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 88a4f99..debd309 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -540,6 +540,15 @@ static struct dmi_system_id video_dmi_table[] __initdata = {
 		DMI_MATCH(DMI_PRODUCT_NAME, "730U3E/740U3E"),
 		},
 	},
+	{
+	 /* https://bugs.freedesktop.org/show_bug.cgi?id=87286 */
+	 .callback = video_disable_native_backlight,
+	 .ident = "SAMSUNG 900X3C/900X3D/900X3E/900X4C/900X4D",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "SAMSUNG ELECTRONICS CO., LTD."),
+		DMI_MATCH(DMI_PRODUCT_NAME, "900X3C/900X3D/900X3E/900X4C/900X4D"),
+		},
+	},
 
 	{
 	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1163574 */
-- 
2.1.4