Since version 3.17.1 of the kernel, the minimum backlight brightness I can get using either the backlight keys or xbacklight is too high to be comfortable in the evening (even with the roomlights on). Downgrading to 3.16.4 solves the issue. With 3.17.1, this high brightness corresponds to a 0 value for /sys/class/backlight/intel_backlight/actual_brightness and /sys/class/backlight/intel_backlight/brightness , whereas with 3.16.4, the lowest value I can get there is 8, which is way darker (but still readable in the dark) than what 3.17.1 calls “0”. It could be useful to mention that the backlight keys work with “video.use_native_backlight=0”, but not with this setting set to 1, nor with “acpi_backlight=vendor” + “acpi_osi=linux” (but I can still use xbacklight with these settings). Changing these options has no effect on the minimum brightness. I'm using ArchLinux, the packages being: - for 3.17.1: linux 3.17.1-1, build date: 2014-10-15 13:06 UTC - for 3.16.4: linux 3.16.4-1, build date: 2014-10-06 08:26 CEST. My computer is a Notebook W65_67SZ, with Intel HD Graphics 4600.
Details in commit 6dda730e55f412a6dfb181cae6784822ba463847 Author: Jani Nikula <jani.nikula@intel.com> Date: Tue Jun 24 18:27:40 2014 +0300 drm/i915: respect the VBT minimum backlight brightness
How's v3.19 kernel?
Timeout.