A nice, overdue usability improvement is on the way for those using Apple Macs under Linux. Finally there will be the ability to preserve the same backlight brightness across reboots under Linux.
Currently when rebooting a Mac with adjustable display brightness under Linux, the brightness level is not saved and thus reboots and ends up being set to whatever was the last brightness value set by macOS. But two small patches to the Linux EFI code will allow saving the brightness on Macs under Linux.
Atharva Tiwari posted the patches to write the brightness value to the EFI variable “backlight-level” for overcoming this behavior. Thus on boot the backlight-level is then properly restored to avoid any unexpected brightness changes to the display across reboots.
See this patch series for those interested in this EFI addition to avoid any jarring backlight changes across Mac reboots.
