From d21a91629f4b8e794fc4c0e0c17c85cedf1d806c Mon Sep 17 00:00:00 2001
From: Hans de Goede <hdegoede@redhat.com>
Date: Tue, 17 Dec 2019 20:08:11 +0100
Subject: [PATCH] ACPI: video: Do not export a non working backlight interface on MSI MS-7721 boards
Git-commit: d21a91629f4b8e794fc4c0e0c17c85cedf1d806c
Patch-mainline: v5.6-rc1
References: bsc#1051510

Despite our heuristics to not wrongly export a non working ACPI backlight
interface on desktop machines, we still end up exporting one on desktops
using a motherboard from the MSI MS-7721 series.

I've looked at improving the heuristics, but in this case a quirk seems
to be the only way to solve this.

While at it also add a comment to separate the video_detect_force_none
entries in the video_detect_dmi_table from other type of entries, as we
already do for the other entry types.

Cc: All applicable <stable@vger.kernel.org>
Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=1783786
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/acpi/video_detect.c |   13 +++++++++++++
 1 file changed, 13 insertions(+)

--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -311,6 +311,11 @@ static const struct dmi_system_id video_
 		DMI_MATCH(DMI_PRODUCT_NAME, "Vostro V131"),
 		},
 	},
+
+	/*
+	 * Desktops which falsely report a backlight and which our heuristics
+	 * for this do not catch.
+	 */
 	{
 	 /* https://bugzilla.redhat.com/show_bug.cgi?id=1123661 */
 	 .callback = video_detect_force_native,
@@ -328,6 +333,14 @@ static const struct dmi_system_id video_
 		DMI_MATCH(DMI_PRODUCT_NAME, "OptiPlex 9020M"),
 		},
 	},
+	{
+	 .callback = video_detect_force_none,
+	 .ident = "MSI MS-7721",
+	 .matches = {
+		DMI_MATCH(DMI_SYS_VENDOR, "MSI"),
+		DMI_MATCH(DMI_PRODUCT_NAME, "MS-7721"),
+		},
+	},
 	{ },
 };