Laptop backlight is turning to 100% after exit of a lock screen or user switch – Samsung Ative Book 6.
Submitted by marciosr
Created attachment 309278 dmesg
When I go back of a screen lock (or after a user switch or after system return to a sleep), the screen brightness is changed to 100%. The backlight level is saved after system boot, just the lock screen changes it.
The slider control shows the prior correct level and the command /usr/lib/gnome-settings-daemon/gsd-backlight-helper –get-brightness shows that too.
I'm using an updated Arch Linux and that behavior is the same with kernel linux-lts (version 3.14.49) and the main kernel (version 4.1.4).
Blacklisting the module samsung_backlight don't change anything.
Various combinations of boot parameters ( video.use_native_backlight=0 systemd.restore_state=1, acpi_backlight=vendor, video.disable_backlight_sysfs_if=1) don't change anything ether.
Using gnome 3.16.2 and gnome-settings-daemon 3.16.3.
Attachment 309278, "dmesg":