mostly can't rotate external monitor with Display Settings

[Hans-Christoph Steiner]

I have a Dell m3800 running Loki that is fully updated as of today. I use in a Dell U2410 monitor via HDMI. The whole screen can physically rotate, so I also want to set the rotation in Display Settings. Occasionally this works, mostly it does not. For example, if I plug in the monitor, and it shows up as present but disabled, I go to the monitor menu to enable it, and the only rotation option is "None". Then when I enable the monitor, that works fine, and then I have the proper rotation options for that monitor. But when I tried arranging the monitor layout or changing the rotation options, it often does not enable the Apply button. Clicking "Detect Monitors" seems to do nothing.

I then tried `xrandr --output HDMI1 --rotate left`, and that worked perfectly.

I was having issues with sleep/suspend, so I installed bbswitch, turned off the nvidia card, uninstalled xserver-xorg-video-nouveau and blacklisted the kernel module, e.g. `blacklist nouveau`.

[Hans-Christoph Steiner (eighthave)]

I should add, I also do not have the nvidia drivers installed:

$ dpkg -l *nouveau*
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-=============================-===================-===================-================================================================
ii libdrm-nouveau2:amd64 2.4.70-1~ubuntu16.0 amd64 Userspace interface to nouveau-specific kernel DRM services -- r
 ~ $ dpkg -l *nvidia*
Desired=Unknown/Install/Remove/Purge/Hold
| Status=Not/Inst/Conf-files/Unpacked/halF-conf/Half-inst/trig-aWait/Trig-pend
|/ Err?=(none)/Reinst-required (Status,Err: uppercase=bad)
||/ Name Version Architecture Description
+++-=============================-===================-===================-================================================================
un nvidia-common <none> <none> (no description available)
un nvidia-legacy-340xx-vdpau-dri <none> <none> (no description available)
un nvidia-prime <none> <none> (no description available)
un nvidia-vdpau-driver <none> <none> (no description available)
 ~ $