[Intel-gfx] drm i915 weirdness with /sys/class/drm/card0*/status

[Dave Airlie]

> 
> > > The biggest change here is 4.1 stopped forcing the probe from sysfs
> > > precisely because systemd was hitting them so often for illogical
> > > reasons (being docked depends on having the lid open and an
> > > external display connected!). To force the probe, you must do
> > > 	$ echo detect > /sys/class/drm/*/status
> > 
> > Oh right I've forgotten about that one. For reference the commit is:
> 
> So, there's definitely a bug here somewhere: the status field stays at
> "unknown" continously on mylaptop after coming back from a
> suspend. X11 doesn't do the "echo detect", the kernel doesn't do it,
> and neither does logind. Nothing apparently does. But something really
> should.

Real drm KMS users don't need to do this, X should just do a normal ioctl
on the device and cause it to happen, 

echoing detect is only a backdoor for external non-KMS fd opening users,

Just clarifying, clearly there is a bug here with the unknowns getting
stuck on, hopefully someone can reproduce it and fix it

Dave.