Brightness changes during use

[Stormageddon0]

On my deck, making the brightness file read-only does not prevent steam from changing the brightness. When "Enable Adaptive Brightness" in display settings is on, steam raises the brightness in a bright environment on its own while this script is running.

I can reproduce this manually with the following steps:

1. Close Virtualhere client on PC. (so that VirtualHere does not steal control)
2. Run deckpad from gamemode.
3. Enter sudo password.
4. Hold "steam" or "..." and push left joystick up to raise brightness

I believe that steam does not use the brightness file in sysfs to alter the brightness, but rather communicates with the driver/kernel directly I don't know if there is another way to prevent steam from making brightness changes, perhaps the script could work around this by periodically changing the brightness back to minimum.