I found a bug in brightness control. According to wsconsctl, display
brightness is initially set to 90%:
# wsconsctl | grep brightness
wsconsctl: Use explicit arg to view keyboard.map.
display.brightness=90.00%
#
If I lower the brightness, wsconsctl says it has lowered it:
# wsconsctl display.brightness=10
display.brightness -> 10.00%
# wsconsctl | grep brightness
wsconsctl: Use explicit arg to view keyboard.map.
display.brightness=10.00%
#
But even if wsconsctl says that now brightness has been set to 10%,
the brightness of my display has not changed.
Same thing if try to change the brightness in Xorg with xbacklight:
$ xrandr --prop
Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
eDP1 connected 1366x768+0+0 (normal left inverted right x axis y axis)
344mm x 194mm
[...]
BACKLIGHT: 90
range: (0, 100)
Backlight: 90
range: (0, 100)
scaling mode: Full aspect
supported: None, Full, Center, Full aspect
Broadcast RGB: Full
supported: Full, Limited 16:235
audio: auto
supported: force-dvi, off, auto, on
1366x768 60.0*+
1024x768 60.0
800x600 60.3 56.2
640x480 59.9
[...]
$ xbacklight -set 10%
$ xrandr --prop
Screen 0: minimum 320 x 200, current 1366 x 768, maximum 8192 x 8192
eDP1 connected 1366x768+0+0 (normal left inverted right x axis y axis)
344mm x 194mm
[...]
BACKLIGHT: 10
range: (0, 100)
Backlight: 10
range: (0, 100)
scaling mode: Full aspect
supported: None, Full, Center, Full aspect
Broadcast RGB: Full
supported: Full, Limited 16:235
audio: auto
supported: force-dvi, off, auto, on
1366x768 60.0*+
1024x768 60.0
800x600 60.3 56.2
640x480 59.9
[...]
$
According to xrandr brightness has been changed, but this is wrong.
The brightness of my display did not change.
In case the issue is related to acpi, here I uploaded a dmesg from a
-current kernel built with "ACPI_DEBUG":
https://drive.google.com/file/d/0B5nVEarf-0aCeUVvQWdiUjRJYW8/edit?usp=sharing
