ACPI / video: Fix use_native_backlight selection logic

commit 25294e9f00f03b2b4f4c56e913bc8c573972f33b upstream.

Commit 751109aad583 ("ACPI / video: Change the default for
video.use_native_backlight to 1") has changed the default for
use_native_backlight from 0 to 1, but instead of changing
use_native_backlight_dmi to true, and leaving use_native_backlight_param at -1,
it has changed use_native_backlight_param to 1.

This causes acpi_video_use_native_backlight() to always think that a value was
specified through the param, making it impossible to add a dmi based quirk
to force 0 now that the default is 1.

This fixes this by restoring the use_native_backlight_param default to -1, and
instead setting the use_native_backlight_dmi default to true.

Fixes: 751109aad583 (ACPI / video: Change the default for video.use_native_backlight to 1)
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.c b/drivers/acpi/video.c
index 350d52a8f7811452142e87564e8ebd2b11cab2f0..2c5af1c817b462fdfe871686406bda72d33e53a3 100644 (file)
--- 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;