From: Hans de Goede hdegoede@redhat.com
[ Upstream commit fb1836c91317e0770950260dfa91eb9b2170cb27 ]
When available prefer native backlight control over vendor backlight control.
Testing has shown that there are quite a few laptop models which rely on native backlight control (they don't have ACPI video bus backlight control) and on which acpi_osi_is_win8() returns false.
Currently __acpi_video_get_backlight_type() returns vendor on these laptops, leading to an empty /sys/class/backlight.
As a workaround for this acpi_video_backlight_use_native() has been temporarily changed to always return true.
This re-introduces the problem of having multiple backlight devices under /sys/class/backlight for a single panel.
Change __acpi_video_get_backlight_type() to prefer native over vendor when available. So that it returns native on these models.
And change acpi_video_backlight_use_native() back to only return true when __acpi_video_get_backlight_type() returns native.
Signed-off-by: Hans de Goede hdegoede@redhat.com Signed-off-by: Rafael J. Wysocki rafael.j.wysocki@intel.com Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/acpi/video_detect.c | 18 +++--------------- 1 file changed, 3 insertions(+), 15 deletions(-)
diff --git a/drivers/acpi/video_detect.c b/drivers/acpi/video_detect.c index 0c17ee93f861..76b7e7f8894e 100644 --- a/drivers/acpi/video_detect.c +++ b/drivers/acpi/video_detect.c @@ -795,10 +795,10 @@ static enum acpi_backlight_type __acpi_video_get_backlight_type(bool native) return acpi_backlight_video;
/* Use native if available */ - if (native_available && prefer_native_over_acpi_video()) + if (native_available) return acpi_backlight_native;
- /* No ACPI video (old hw), use vendor specific fw methods. */ + /* No ACPI video/native (old hw), use vendor specific fw methods. */ return acpi_backlight_vendor; }
@@ -810,18 +810,6 @@ EXPORT_SYMBOL(acpi_video_get_backlight_type);
bool acpi_video_backlight_use_native(void) { - /* - * Call __acpi_video_get_backlight_type() to let it know that - * a native backlight is available. - */ - __acpi_video_get_backlight_type(true); - - /* - * For now just always return true. There is a whole bunch of laptop - * models where (video_caps & ACPI_VIDEO_BACKLIGHT) is false causing - * __acpi_video_get_backlight_type() to return vendor, while these - * models only have a native backlight control. - */ - return true; + return __acpi_video_get_backlight_type(true) == acpi_backlight_native; } EXPORT_SYMBOL(acpi_video_backlight_use_native);