Monitor No-Longer Detected When Turned Off

Graphics / Linux Linux
1

Linux 4.16.5, Nvidia 390.48 on a GTX 1060.

Historically my machine would see the monitor even when the monitor was turned off, as the EDID chip in the display is powered by the attached device (e.g. your PC) not the device itself. But I’ve just noticed this has stopped working:

Screen 0: minimum 8 x 8, current 640 x 480, maximum 32767 x 32767
DVI-D-0 disconnected primary (normal left inverted right x axis y axis)
HDMI-0 disconnected (normal left inverted right x axis y axis)
HDMI-1 disconnected (normal left inverted right x axis y axis)
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)

Turning the projector back on shows what I’d expect:

Screen 0: minimum 8 x 8, current 1920 x 1080, maximum 32767 x 32767
DVI-D-0 disconnected primary (normal left inverted right x axis y axis)
HDMI-0 disconnected (normal left inverted right x axis y axis)
HDMI-1 connected 1920x1080+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1920x1080     60.00*+  59.94    50.00    29.97    25.00    23.98    60.05    60.00    50.04
   1600x1200     60.00
   1440x900      59.89
   1280x1024     75.02    60.02
   1280x800     119.91    59.81
   1280x720      60.00    59.94    50.00
   1024x768     119.99    75.03    70.07    60.00
   800x600       75.00    72.19    60.32
   720x576       50.00
   720x480       59.94
   640x480       75.00    72.81    59.94    59.93
DP-0 disconnected (normal left inverted right x axis y axis)
DP-1 disconnected (normal left inverted right x axis y axis)
DP-2 disconnected (normal left inverted right x axis y axis)
DP-3 disconnected (normal left inverted right x axis y axis)

Thing is this is a new issue. Historically, even if the projector was off, I’d see what’s shown in the second output regardless of whether the projector was turned on or not as long as it was physically connected (via HDMI in this case).

I often access the machine over VNC and the projector is normally off, so obviously this poses a problem for me.

Is this an Nvidia driver change, or possibly a kernel/Xorg change?