I made a couple more tests and here is what I've found out. When the backlight is managed by radeon, writing to /sys/class/backlight/radeon_bl0/brightness doesn't do anything. Although changing brightness with Fn+Left/Fn+Right works but the value in /sys/class/backlight/radeon_bl0/brightness doesn't match the actual brightness at all: it can be 250 but the screen would be really dim and vice versa.
When I use the kernel without radeon and drm so the backlight is managed by acpi_video, writing to "/sys/class/backlight/acpi_video0/brightness" works fine, the value is saved and restored properly unless it was set to the maximum. In both cases the brightness is reset on shutdown to the lowest possible value and it's always the same on the bios boot screen. -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1912887 Title: Acer Aspire 5742g backlight brightness level is not saved on shutdown To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1912887/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
