1 files changed, 43 insertions, 2 deletions

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 826884392e6b..fcbda105616e 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -82,9 +82,9 @@ module_param(allow_duplicates, bool, 0644);
  * For Windows 8 systems: used to decide if video module
  * should skip registering backlight interface of its own.
  */
-static int use_native_backlight_param = 1;
+static int use_native_backlight_param = -1;
 module_param_named(use_native_backlight, use_native_backlight_param, int, 0444);
-static bool use_native_backlight_dmi = false;
+static bool use_native_backlight_dmi = true;
 
 static int register_count;
 static struct mutex video_list_lock;
@@ -417,6 +417,12 @@ static int __init video_set_use_native_backlight(const struct dmi_system_id *d)
         return 0;
 }
 
+static int __init video_disable_native_backlight(const struct dmi_system_id *d)
+{
+        use_native_backlight_dmi = false;
+        return 0;
+}
+
 static struct dmi_system_id video_dmi_table[] __initdata = {
         /*
          * Broken _BQC workaround http://bugzilla.kernel.org/show_bug.cgi?id=13121
@@ -720,6 +726,41 @@ static struct dmi_system_id video_dmi_table[] __initdata = {
                 DMI_MATCH(DMI_PRODUCT_NAME, "HP EliteBook 8780w"),
                 },
         },
+
+        /*
+         * These models have a working acpi_video backlight control, and using
+         * native backlight causes a regression where backlight does not work
+         * when userspace is not handling brightness key events. Disable
+         * native_backlight on these to fix this:
+         * https://bugzilla.kernel.org/show_bug.cgi?id=81691
+         */
+        {
+         .callback = video_disable_native_backlight,
+         .ident = "ThinkPad T420",
+         .matches = {
+                DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+                DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T420"),
+                },
+        },
+        {
+         .callback = video_disable_native_backlight,
+         .ident = "ThinkPad T520",
+         .matches = {
+                DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+                DMI_MATCH(DMI_PRODUCT_VERSION, "ThinkPad T520"),
+                },
+        },
+
+        /* The native backlight controls do not work on some older machines */
+        {
+         /* https://bugs.freedesktop.org/show_bug.cgi?id=81515 */
+         .callback = video_disable_native_backlight,
+         .ident = "HP ENVY 15 Notebook",
+         .matches = {
+                DMI_MATCH(DMI_SYS_VENDOR, "Hewlett-Packard"),
+                DMI_MATCH(DMI_PRODUCT_NAME, "HP ENVY 15 Notebook PC"),
+                },
+        },
         {}
 };