[PATCH] ACPI: video: Do not export a non working backlight interface on MSI MS-7721 boards

* [PATCH] ACPI: video: Do not export a non working backlight interface on MSI MS-7721 boards
@ 2019-12-17 19:08 Hans de Goede
       [not found] ` <20191225235530.C65AD20838@mail.kernel.org>
  0 siblings, 1 reply; 2+ messages in thread
From: Hans de Goede @ 2019-12-17 19:08 UTC (permalink / raw)
  To: Rafael J . Wysocki, Len Brown; +Cc: Hans de Goede, linux-acpi, stable

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: stable@vger.kernel.org
BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1783786
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
 drivers/acpi/video_detect.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index 31014c7d3793..e63fd7bfd3a5 100644
--- a/drivers/acpi/video_detect.c
+++ b/drivers/acpi/video_detect.c
@@ -336,6 +336,11 @@ static const struct dmi_system_id video_detect_dmi_table[] = {
 		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_detect_dmi_table[] = {
 		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"),
+		},
+	},
 	{ },
 };
 
-- 
2.23.0


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