I searched and found similar issues from years ago but the fixes do not work. I have a new Dell XPS 15 running elementary OS 5.1.7 and the brightness controls do not work. Here's what nvidia-smi is reporting:
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 450.142.00 Driver Version: 450.142.00 CUDA Version: 11.0 |
|-------------------------------+----------------------+----------------------+
| GPU Name Persistence-M| Bus-Id Disp.A | Volatile Uncorr. ECC |
| Fan Temp Perf Pwr:Usage/Cap| Memory-Usage | GPU-Util Compute M. |
| | | MIG M. |
|===============================+======================+======================|
| 0 GeForce GTX 1650 Off | 00000000:01:00.0 Off | N/A |
| N/A 46C P0 5W / N/A | 5MiB / 3914MiB | 0% Default |
| | | N/A |
+-------------------------------+----------------------+----------------------+
+-----------------------------------------------------------------------------+
| Processes: |
| GPU GI CI PID Type Process name GPU Memory |
| ID ID Usage |
|=============================================================================|
| 0 N/A N/A 1161 G /usr/lib/xorg/Xorg 4MiB |
+-----------------------------------------------------------------------------+
...and neofetch:
OS: elementary OS 5.1.7 Hera x86\_64
Host: XPS 15 7590
Kernel: 5.4.0-80-generic
GPU: NVIDIA NVIDIA Corporation Device 1f91
GPU: Intel Device 39b Memory: 2276MiB / 15647MiB
Any ideas on how to fix this?