Bug reappeared in 18.04. Dell Precision M4800, running the standard Ubuntu Gnome shell desktop (on Xorg), Intel Graphics. No issues in 16.04 (or perhaps a tiny delay?), but unworkable in 18.04.
Both Fn-Up/Down and `echo value | sudo tee brightness` exhibit the delay (~2-3 seconds normally). Notable is that the brightness seems to change *immediately* after echoing into sysfs, so all the delay occurs in the return of the call back to the prompt. In /sys/class/backlight I have only intel_backlight. No difference with or without Backlight option in xorg.conf, nor with the acpi_backlight=vendor kernel param. Also notable: when performing the brightness change in a virtual terminal, it is *instantaneous*. The issue only occurs in the graphical VT running the desktop environment. -- You received this bug notification because you are a member of Ubuntu Desktop Bugs, which is subscribed to gnome-power-manager in Ubuntu. https://bugs.launchpad.net/bugs/847001 Title: Adjusting display brightness is very slow on several Dell laptops To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/gnome-power-manager/+bug/847001/+subscriptions -- desktop-bugs mailing list desktop-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/desktop-bugs
