How to Enable Brightness Controls on iMac Mid 2011 with Ubuntu 22.04

December 11, 2023

If you’ve installed Ubuntu 22.04 on your iMac mid 2011 and encountered issues adjusting the brightness like I did, follow these steps to activate brightness controls:

Steps:

1. Open Terminal and access the /etc/default directory:

   sudo nano /etc/default/grub

2. Locate the line:

   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

3. Modify it to include additional parameters:

   The line below sets the default kernel parameters for booting. It includes parameters like “quiet” (to suppress most boot messages), “splash” (to show the boot splash screen), and specific settings related to power management and backlight control for ACPI (Advanced Configuration and Power Interface).

   GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force acpi_backlight=native"

4. Update the GRUB configuration:

   sudo update-grub

5. Reboot your system.

These steps adjust the GRUB configuration to include specific parameters, allowing brightness controls to function properly on your iMac mid 2011 running Ubuntu 22.04.

This method was successfully tested on an Apple iMac “Core i7” 3.4 27” (Mid-2011) Specs Identifiers: Mid-2011 - MD063LL/A - iMac12,2 - A1312 - 2429 running Ubuntu 22.04.3 LTS.