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

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>

diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c
index 31014c7..e63fd7b 100644 (file)
--- 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"),
+               },
+       },
        { },
 };