1 files changed, 30 insertions, 6 deletions

diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 26eb70c8f518..cc79d3fedfb2 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -82,9 +82,15 @@ 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;
+enum {
+        NATIVE_BACKLIGHT_NOT_SET = -1,
+        NATIVE_BACKLIGHT_OFF,
+        NATIVE_BACKLIGHT_ON,
+};
+
+static int use_native_backlight_param = NATIVE_BACKLIGHT_NOT_SET;
 module_param_named(use_native_backlight, use_native_backlight_param, int, 0444);
-static bool use_native_backlight_dmi = true;
+static int use_native_backlight_dmi = NATIVE_BACKLIGHT_NOT_SET;
 
 static int register_count;
 static struct mutex video_list_lock;
@@ -237,15 +243,16 @@ static void acpi_video_switch_brightness(struct work_struct *work);
 
 static bool acpi_video_use_native_backlight(void)
 {
-        if (use_native_backlight_param != -1)
+        if (use_native_backlight_param != NATIVE_BACKLIGHT_NOT_SET)
                 return use_native_backlight_param;
-        else
+        else if (use_native_backlight_dmi != NATIVE_BACKLIGHT_NOT_SET)
                 return use_native_backlight_dmi;
+        return acpi_osi_is_win8();
 }
 
 bool acpi_video_verify_backlight_support(void)
 {
-        if (acpi_osi_is_win8() && acpi_video_use_native_backlight() &&
+        if (acpi_video_use_native_backlight() &&
             backlight_device_registered(BACKLIGHT_RAW))
                 return false;
         return acpi_video_backlight_support();
@@ -414,7 +421,13 @@ static int __init video_set_bqc_offset(const struct dmi_system_id *d)
 
 static int __init video_disable_native_backlight(const struct dmi_system_id *d)
 {
-        use_native_backlight_dmi = false;
+        use_native_backlight_dmi = NATIVE_BACKLIGHT_OFF;
+        return 0;
+}
+
+static int __init video_enable_native_backlight(const struct dmi_system_id *d)
+{
+        use_native_backlight_dmi = NATIVE_BACKLIGHT_ON;
         return 0;
 }
 
@@ -559,6 +572,17 @@ static struct dmi_system_id video_dmi_table[] __initdata = {
                 DMI_MATCH(DMI_PRODUCT_NAME, "XPS L521X"),
                 },
         },
+
+        /* Non win8 machines which need native backlight nevertheless */
+        {
+         /* https://bugzilla.redhat.com/show_bug.cgi?id=1187004 */
+         .callback = video_enable_native_backlight,
+         .ident = "Lenovo Ideapad Z570",
+         .matches = {
+                DMI_MATCH(DMI_SYS_VENDOR, "LENOVO"),
+                DMI_MATCH(DMI_PRODUCT_NAME, "102434U"),
+                },
+        },
         {}
 };