(In reply to comment #10)
> > For systems where this is a regression, can you bisect?
> 
> I don't understand. Could you explain this question please (if it was to me)?

If it worked with an older kernel, you can use git to bisect between working
kernel and the the broken one.  Bisecting allows you to pinpoint the change
that caused the problem.  There are a number of good tutorials on using git to
bisect a problem.