Did this issue start happening after an update/upgrade? Was there a prior kernel version where you were not having this particular problem?
Would it be possible for you to test the latest upstream kernel? Refer to https://wiki.ubuntu.com/KernelMainlineBuilds . Please test the latest v4.20 kernel[0]. If this bug is fixed in the mainline kernel, please add the following tag 'kernel-fixed-upstream'. If the mainline kernel does not fix this bug, please add the tag: 'kernel-bug-exists-upstream'. Once testing of the upstream kernel is complete, please mark this bug as "Confirmed". Thanks in advance. [0] http://kernel.ubuntu.com/~kernel-ppa/mainline/v4.20-rc2 ** Changed in: linux (Ubuntu) Importance: Undecided => Medium -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to linux in Ubuntu. https://bugs.launchpad.net/bugs/1782177 Title: Screen sometimes jumps to full brightness on resume from suspend Status in linux package in Ubuntu: Incomplete Bug description: At night, I usually turn my brightness down as far as it will go using the brightness keys. This makes it dim, but visible and not off. When I walk away for a while, the screen goes to sleep, and when I come back and move the mouse, the screen jumps to full brightness, which is very unpleasant at night. Investigating, it seems that the brightness in intel_backlight is getting reset to 4437, but the one in acpi_video0 reads 0. $ for file in brightness max_brightness actual_brightness; > do > for directory in /sys/class/backlight/intel_backlight/ /sys/class/backlight/acpi_video0/ > do > echo $directory$file : $(cat $directory$file) > done > done /sys/class/backlight/intel_backlight/brightness : 4437 /sys/class/backlight/acpi_video0/brightness : 0 /sys/class/backlight/intel_backlight/max_brightness : 4437 /sys/class/backlight/acpi_video0/max_brightness : 15 /sys/class/backlight/intel_backlight/actual_brightness : 4437 /sys/class/backlight/acpi_video0/actual_brightness : 0 After I press the button to increase the brightness one notch, they are back in sync, and then I can turn it back down as well. $ for file in brightness max_brightness actual_brightness; > do > for directory in /sys/class/backlight/intel_backlight/ /sys/class/backlight/acpi_video0/ > do > echo $directory$file : $(cat $directory$file) > done > done /sys/class/backlight/intel_backlight/brightness : 53 /sys/class/backlight/acpi_video0/brightness : 1 /sys/class/backlight/intel_backlight/max_brightness : 4437 /sys/class/backlight/acpi_video0/max_brightness : 15 /sys/class/backlight/intel_backlight/actual_brightness : 53 /sys/class/backlight/acpi_video0/actual_brightness : 1 This is on a fresh install of xubuntu 18.04. Seems like a regression from 16.04, which I ran on the same laptop without this issue. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1782177/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp