I installed Debian 12 with KDE on a 2013 iMac. I just love the new system, except I can’t adjust screen brightness. So far I have spent several hours trying.
- There are no brightness controls in the KDE settings.
- xbacklight reports: “No outputs have backlight property”.
- ddcutil reports: “invalid display”, “DDC communication failed”.
- xgamma is unable to make any changes.
- sys/class/backlight is empty.
System specs:
- KDE Plasma 5.27.5
- KDE Frameworks 5.103.0
- Qt 5.15.8
- Linux Kernel 6.1.0-34-amd64 (64-bit)
- Graphics Platform: Wayland
- Graphics Processor: NVE7
- Graphics controller: NVIDIA Corporation GK107M [GeForce GT 750M Mac Edition] (rev a1)
- Computer: iMac 14,3 (late 2013)
Display details:
- description: VGA compatible controller
- product: GK107M [GeForce GT 750M Mac Edition]
- vendor: NVIDIA Corporation
- physical id: 0
- bus info: pci@0000:01:00.0
- logical name: /dev/fb0
- version: a1
- width: 64 bits
- clock: 33MHz
- capabilities: pm msi pciexpress vga_controller bus_master cap_list rom fb
- configuration: depth=32 driver=nouveau latency=0 resolution=1920,1080
– resources: irq:56 memory:b0000000-b0ffffff memory:90000000-9fffffff memory:a0000000-a1ffffff ioport:2000(size=128) memory:b1000000-b107ffff
