Unable to change brightness on Lenovo thinkpad P1 Gen 5

Nvidia Driver Version : 525.60.11
OS: Arch linux
linux kernel: 6.0.12
Graphics mode : Discrete

I’m unable to change brightness on my laptop when the graphics is in Discrete mode, i manually tried to change value in /sys/class/backlight/nvidia_0/brightness file, but did not make a difference. I have added nvidia.NVreg_EnableBacklightHandler=1 to my kenel params, but even that did not do any difference. Please help me out.

Please check for a bios update.
Please check if setting kernel parameter
enables backlight control.

This did not change much.
But i observed one thing, i’m able to change the brightness after a S3 suspend and resume. The behavior is the same with or without the kernel parameter you suggested.
So for me to able to change the brightness after restart of the system i need suspend/resume once , after which it starts working. Weird bug.

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