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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Hans de Goede <hdegoede@redhat.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>
Subject: [PATCH 5.5 095/367] ACPI: video: Do not export a non working backlight interface on MSI MS-7721 boards
Date:   Mon, 10 Feb 2020 04:30:08 -0800
Message-Id: <20200210122433.134091289@linuxfoundation.org>
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From: Hans de Goede <hdegoede@redhat.com>

commit d21a91629f4b8e794fc4c0e0c17c85cedf1d806c upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -336,6 +336,11 @@ static const struct dmi_system_id video_
 		DMI_MATCH(DMI_PRODUCT_NAME, "Precision 7510"),
 		},
 	},
+
+	/*
+	 * Desktops which falsely report a backlight and which our heuristics
+	 * for this do not catch.
+	 */
 	{
 	 .callback = video_detect_force_none,
 	 .ident = "Dell OptiPlex 9020M",
@@ -344,6 +349,14 @@ 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"),
+		},
+	},
 	{ },
 };