Bug#942219: systemd-backlight at backlight:dell_backlight.service fails at boot for dell d600, d620, d820

[Rado Q]

Package: systemd
Version: 241-7~deb10u1

Dear Maintainer,
   * What led up to the situation?
Installation of debian10.

   * What exactly did you do (or not do) that was effective (or ineffective)?
Boot.

   * What was the outcome of this action?
Failed systemd-backlight at backlight:dell_backlight.service .

   * What outcome did you expect instead?
Startup without failure.


This happens with dell d600, d620, d820.
It works OK for dell vostro 1520.

How to get more info?