System info:
- machine: HP Pavilion Gaming Laptop 15-ec0xxx
- kernel: Linux 6.12.5-2-cachyos
brightnessctl output: Device ‘amdgpu_bl1’ of class ‘backlight’: Current brightness: 78 (31%) Max brightness: 255
After the recent kernel update what I have observed is that after system wakes up from sleep the screen backlight doesn’t work properly. The problem is a little weird. The restored brightness after waking up appears to be something like 40% or 50% even when I have set it to zero. And only after 50%, actually setting it to 50%, does it increase. This has been happening to both my KDE plasma and Hyprland installs. Is this a kernel thing, a distro thing, or a DE/WM thing? And is there any solution?
edit: typo
It gives me the following output:
$ ddcutil detect
output :
Invalid display
I2C bus: /dev/i2c-5
DRM connector: card1-eDP-1
EDID synopsis:
Mfg id: NCP - UNK
Model:
Product code: 64 (0x0040)
Serial number:
Binary serial number: 0 (0x00000000)
Manufacture year: 2018, Week: 1
This is a laptop display. Laptop displays do not support DDC/CI
Well, the issue is, a I said, a little tricky. brightnessctl works as expected during the initial boot. After the system go into sleep/hibernation, however, the backlight “appears” to be at 40% or 50% and does not seem to go lower that that. It goes up, but not down. Even when executing the brightnessctl command it gives the “correct” output but the brightness still does not go down.
Its confusing…