This is my ugly workaround for a brightness issue present in laptops with OLED screens.

On certain laptops with display brightness controlled by intel_backlight,
when setting the brightness to 0 through the sysfs interface,
which is also used by several userland applications, the screen turns off.
Then when trying to turn it back on with the brightness controls, it does not turn on again.

The issue seems to be related to OLED screens. Models found to be affected so far:
 - Dell XPS13 9310
 - Dell XPS15 9510
 - Xiaomi Book Pro 14
 - Lenovo X1 Carbon Gen 10

Interesting bug reports:
 - https://gitlab.freedesktop.org/drm/intel/-/issues/3657
 - https://gitlab.freedesktop.org/drm/intel/-/issues/4949

This workaround comes in the form of a module that hooks into the kernel,
where it changes the brightness argument to 1 in case a 0 was passed.

To build this module, simply do:
   make
To subsequently install the module, do:
   sudo make install

You may want to have the module automatically built and installed each time you
update your kernel through your package manager.
To facilitate this, convenience build targets for dkms are present.

To register this module with dkms and install it, do:
   sudo make dkms
If you're not happy with it, you can remove it again with:
   sudo make dkms_remove

Once installed, you should be able to load the module with:
   sudo modprobe intel_backlight_fix
At this point, the brighness issue should be fixed for your screen.

Finally, in order to have the module loaded automatically on startup,
you may add it to /etc/modules.