Comment 34 for bug 311716

This is three stage:
- fix for OP's problem (bug #257827) which resulted in regression for some others (initial report here and in the other
  report)
- avoid those problems and get regressions for yet other laptops

The main regression would be the initial change but reverting that would be again a bigger change (which causes another ABI bump which should also be rather avoided) and would also revert a state that is actually upstream, which also might be sub-optimal. The fix-for-the-fix though is still discussed upstream. So the best way to proceed I can see at the moment (if settings available by module options yield results everybody can live with) would be to revert the second patch and add some defaults bsaed on DMI information.
That was the reason to ask whether -11.22 with a certain acpi_backlight setting gives the same results as with -11.23 for those that have a working -11.23.