ACPI / video: Add disable_native_backlight quirk for Dell XPS15 L521X

commit 6a3ef10b upstream.

The L521X variant of the Dell XPS15 has integrated nvidia graphics, and
backlight control does not work properly when using the native interfaces.

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1163574Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

drivers/acpi/video.c

@@ -711,6 +711,16 @@ static struct dmi_system_id video_dmi_table[] __initdata = {
 		DMI_MATCH(DMI_PRODUCT_NAME, "370R4E/370R4V/370R5E/3570RE/370R5V"),
 		},
 	},
+
+	{
+	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1163574 */
+	 .callback = video_disable_native_backlight,
+	 .ident = "Dell XPS15 L521X",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "Dell Inc."),
+		DMI_MATCH(DMI_PRODUCT_NAME, "XPS L521X"),
+		},
+	},
 	{}
 };