From: Hans de Goede <hdegoede@xxxxxxxxxx>
[ 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@xxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
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);
--
2.35.1
