Created attachment 301182 [details] dmesg Brightness control does not work with AMD Ryzen 5600h when using switchable graphics (aka. Hybrid graphics). I currently using a Dell G15 5515 with fedora 36 and Kernel 5.17. CPU: AMD Ryzen 5 5600h with Radeon Graphics GPU: NVIDIA RTX 3050 Mobile Graphics System Memory: 16 GB Display(s): Laptop (Laptop Screen) and Dell secondary Monitor How to reproduce the issue: Enable hybrid graphics/Optimus in BIOS setup, so that the display will be connected to the AMD GPU. Try to change brightness from GNOME or write into /sys/class/backlight/amdgpu_bl1/brightness. The display brightness doesn't change. Looking inside /sys/class/backlight/, there is only one directory amdgpu_bl1. max_brightness is 255. actual_brightness follows the value written into brightness. The amdgpu.backlight=0 kernel parameter mentioned in #1438 (closed) doesn't help here. acpi_backlight=vendor or acpi_backlight=native or acpi_backlight=none makes no difference. With acpi_backlight=video there is another acpi_video0 in addition to amdgpu_bl1 in /sys/class/backlight/ but neither of them has any effect. If hybrid graphics is disabled, the display is connected to the Nvidia GPU, the Nvidia proprietary driver can change the display brightness without problem. In this case there is only nvidia_0 in /sys/class/backlight/ with max_brightness 100. In Windows 10 OS and hybrid graphics mode, the brightness control works if the AMD driver (21.6.1 downloaded from AMD website) is installed and enabled and it doesn't work if the AMD driver is not installed or disabled, regardless of the status of Nvidia driver too.
I have similar hardware (Dell G15 5515 with AMD Ryzen 5800H CPU and Nvidia GPU) and the same problem and symptoms. I, too, have tested with different acpi_backlight parameters to no benefit. I have also uninstalled the proprietary Nvidia driver, and the problem remains, so it's not an issue with out-of-kernel modules. In my case, I am running Arch Linux with the standard kernel. All the 6.0 series of kernels work for me, and none of the 6.1 series do.
Adding acpi_backlight=nvidia_wmi_ec to the kernel command line works around the problem for me. With this option, I am able to control the backlight both with and without the proprietary nvidia module loaded. So, that gives us a workaround, though having this be auto-detected would be preferable.
All good? I'm having the same problem on Pop Os 22.04, can anyone help me how to solve this? How to add this line to the kernel?